In the center of a crater that stretches far beyond the viewable horizon was Kaijuno, who stood frozen in place from the obliterating explosion that had just occurred
All clothing except his mask were scorned into nothing by the sudden combustion. Immediately he covered himself in one of his many spares of his get up as he commissioned a comically large inventory of copies of his clothing set up
Recovering from the explosion, Kaijuno was completely delirious from what had just happened. It wasn't until the being who launched the world destroying explosion levitated downwards was when Kaijuno started to get the picture of what was happening
The floating enraged being was none other then one of the most powerful demons that lived as long as existence itself, the primordial yellow, Jaune who seemed to be short on temper
Kaijuno: Ya know, I personally believe in taking someone out to dinner first before ripping off their clothes.
Jaune: You can count yourself lucky I only held back enough to burn off your clothes. Especially when you kept a lady waiting for so long
Kaijuno: Cmon I never said I was going to immediately head over here. I had a whole festival soon after our meeting. I was busy!
As this bickering was occurring, Diablo reappeared mid air. He released immediately that this argument between the infamous Yellow Primordial and the recently discovered bane of his existence would lead to a headache of conversation that he wasn't in the mood to tolerate
With an audible "Ahem", the primordial black gain the attention of both
Diablo: Excuse me, I'm also here you know
Jaune: Of all people? What are you doing here Noir?
Diablo: I don't go by that anymore, refer to me only by the name that was gifted to me, Diablo
This reveal suprised and set off Jaune that another primordial demon had gained a name prior to her, much to her frustration. She was also baffled at the idea that someone actually named him instead of being named via reputation as with Guy
Diablo: As for why I'm here, you could say what I'm doing is a "recruitment tour" and I've just reached my first stop
Jaune: So you're not here with him?
Diablo: I sincerely wish I wasn't
Immediately catching on to Diablo's frustration, she didn't waste the chance to tease him on it
Jaune: Oh ho ho! Don't tell me Diablo here finally found his own annoyance. About time you get a taste of irritation for once!
Diablo kept himself composed in spite of Jaune's remark. He's set of on presenting himself as a classy and stoic butler set out to do his master's bidding. Denying his annoyances, which is unconvincing the Yellow Primordial
Finally bored of the banter, Jaune questioned us on our visitation. If it was just me, she would already know why but given Diablo's precense into consideration, she was more curious about the details
I briefly explained that I made a bet with Diablo that if I could defeat her, I get the right claim her as my subordinate but if I were to lose, then it will be Diablo's dibs
Jaune: So the jist is that you made this deal for the chance to make me yours? Ha! I would say that's cute but it's honestly way more hilarious
You're still insisting you can casually claim a primordial as a servant?
Kaijuno: I didn't exactly get pummeled the last time we fought, I figured given some prep time, I have a more comfortable shot at least.
Are you saying that's not gonna be the case?
Jaune: Kaijuno, there's something you should know about us demons. Whenever we cross through into the Cardinal World, we're adjusted into a lesser dimensional form that is more appropriate and comprehensible to the dimension of the Cardinal World
In other words, without a proper body vessel to posses, we wouldn't be as strong as we would be normally
The strength I had back then wasn't me at my full power
Hope you made sure to get stronger since then, cause this time, I'll be free from my restraints
Hearing this made me raise a brow underneath my mask. I felt concern about what she said, especially with the venom in her voice as she said this. I figured the difference wouldn't have been too much but with the way she explained it, I'll be in for a rough time
Thankfully I at least did some hellish training over at the ice continent so I gotten a bit sturdier than the last time I encountered Jaune
Diablo could tell things were about to stir up so he flew back a grand amount of distance. It was far enough that to the naked eye, at best visibility he would be a dot in the distance. He knew Jaune well enough that the range of her attacks were considered extreme
With it mainly being me and Jaune now and tensions were at it's breaking point.
In the far surroundings, demons started to reappear after getting blown to bits from Jaune's nuclear explosion. To them, it felt like they woken up from a horrific nightmare. They would end getting a rude awakening when the yellow primordial's second bomb it.
The crater expanded and severely deepened when Jaune didn't hesitate to throw another wave of nuclear magic at the dopey mask demon lord. The surrounding demons that were just revived were killed off again and to go through the revival process all over again
I already applied my Multilayer Barrier to help endure the upcoming explosions and to prevent getting more of my clothes getting incinerated again
Knowing that nuclear was her specialty I chose to immediately close the distance between us to discourage her from resorting to it. I would've rather just use Gojira to consume her nuclear magic but Yagami advised me against this when I asked them for some tips beforehand on how to take Jaune down
With how triggered happy she is about using nuclear magic, I'll play the stalling game by having her waste her magicules over time. She already seen me devour her attacks previously but if I just continuesly devour all of her attacks without issue, she would get the idea that nuclear magic would be useless and resort to other means of defeating me that wouldn't cost her as much magicules
Given how dependent demons are on their magicules supply for combat, the biggest advantage I could gain would be to get her supply low enough to overpower her rather than in punching her really hard, although I would resort to that too
Infact I launched a punch right at her only for her to catch my wrist and thinking I was caught, she thrown a punch in return but I caught her wrist as well.
Both of us gotten a hold of eachother with no intention of letting of the other. With both our hands restrained, Jaune instantly wrapped her legs above my waist to make sure I wouldn't escape as she resorted to headbutt me.
But when her forehead collided with me mask, not only was she blown back but her head was out right shredded away, leaving her decapitated. First time I was able to get a lady to have her face close to mine and she ended up getting her head blown off
I myself was delirious for a moment until Yagami shook me off on why that happened
I was reminded that the mask I was wearing wasn't just a magical mask but was a replica of the mask that Chloe travel back in time with repeatedly for who knows how many times. To the point that it's time compression has reached infinity
It was able to tear up Diablo's arm when he was still an arch demon and Jaune was no different herself
Normally something like this would be death but to a spiritual being and especially a primordial, the loss of a head wasn't fatal and is recoverable
Seeing this as an opening, I pulled out my short sword out of stomach. I had it coated with my demon lord haki along with using Unique Skill Tempest Bond to enhance the elemental magic I applied over my blade as well
I made a b line dash towards her to slash while she was still in shock. But by the time I swing my sword at her, Yagami notified me that she recovered from her shock and to dash back before get reach of her suprise attack
I halted and hastily made some distance between us. Just as I did, Jaune had secretly coating herself in abyss cores and set off an explosion of nuclear magic with her body as the center of the radius. I continued to dash back to avoid the explosion but I was also pushed back from the shockwave
Just as the immediate area was clearing, there was an immediate notice of spatial distortion everywhere. Despite it's name, nuclear magic wasn't just simply an art of srtting off large explosions but it can cause ripples in space and reality if it's intense enough
For the primordial yellow, this can casually be done. As for said primordial, she wasn't really affected by the combustion as it looked like she had the direction of the explosion be focused away from her body to avoid any recoil. It turned out that she used the explosion to give her time to regenerate her head
Getting back my composure from evading the massive radius explosion, I stood in the air keeping a firm grip on my sword in anticipation for Jaune's next move
Once we both gotten a good sight of eachother, Jaune noticed the blade in my hand, she lit up her eyes in excitement
Jaune: No way! You fight with a sword too?
Kaijuno: Yeah? Is sword fight more your specialty?
Jaune: It's more of something I picked to help pass the time. Ya know, existing since the beginning of existence makes one open to new hobbies. Infact one of my top subordinates is actually the one who taught me sword arts
I suspect he's actually a reincarnate given how young he is despite reaching the level of an arch demon and being a master of what he calls the haze style
When Jaune mentioned, I was mildly suprised me this was the case. Yagami did mentioned prior that Jaune would most definitely be skilled in swordsmanship given who one of her subordinates is.
I didn't take Jaune as swordsman, I saw her more as a range magic user given her use for nuclear magic and her getting a gun by the end of Eastern Empire War
Im the next moment, Jaune coated herself in magicules and revealed a change in her outfit. The color of her clothes were a gothic palette. A black that reaches down to her skirt and a pair of gloves with a finger hole for the index finger. On one hand, she wields a long blade sword with colors that matches her outfit
The tone of battle shifted, it was mainly a battle of magic but now it changed to a setting of sword clash
Taking the initiative this time, I closed the distance between us and swung my blade at her once she was in reach. My strike was blocked and parried to which I received a drop kick to my side. I flew far from the kick, if I had bones the most likely case would that all of them would've been broken from that kick
Not giving me a time to rest, Jaune followed me and striked me from above while I was airborne. I managed to block the slash with my own blade but was still pushed back from the strike
Recovering quickly, I launched a flurry of strikes and slashes only to be blocked and at the same time have to evade and block her own attacks
I was getting nowhere in this trade off of attacks. I was left stumped, as this was starting to feel like a stalemate while at the same time it was showing that was the more experienced student between us
It felt like she was teasing me with each time I was getting close to striking her for me to get pushed back. She had a smug look as she was doing it and even whistled at a few of my attempts
Growing impatient and irritated I decided to resort to a sub-skill I had handy in case for a situation like this. Like how Rimuru was struggling against hinata due to her being a superior swordsmen, I used Yagami's sub-skill future attack prediction to help even the odds
Once activated, I could see all of Jaune's upcoming attacks. Now I could return the favor by messing with Jaune. Infact I chose to only resort to blocking just get back at Jaune
Growing her frustration by dragging this out, continuously blocking any attempt for her to attack me, reversing the tide back at her.
Then when she resorted to a downward slash right, it was then I made my move for a suprise
In mid slash, I pulled out my frying pan in my other hand and knocked her sword out of her hand. Then using Universal Shape shift, I instantly rotated my wrist to have the bottom of my pan face Jaune. Just as I knocked her sword, I slammed my pants against her head
The hit was heavy enough to slam her into the ground, making a small crater in the already seemingly endless radius crater below
Before the dust cloud cleared, Jaune already gotten up and dispersed the cloud with a swift stomp
Jaune: So not only did you blew off my head but counting our last encounter you k
now bruised me on both of my cheeks. Seems like you can't enough of my face
Also what did you just hit me with!?
To play it off as something more than just a frying pan, I held a dramatic tone and explained that it's a weapon grand defense and shield perfect for a dual wielder. But I was cut by me off, saying she knew what a frying pan was.
She wasn't convinced by the crap I said
It is basically a really tough frying pan but I don't want anyone else to think that's just the case as well
Suddenly, her sword flew back to the grip of her hand like mjolnir. Now the blade was coated in an intense density of nuclear magic. She isn't playing around anymore
In response, I applied my Monster King Haki along with elemental magic on both of my weapons. I even used Tempest Bond's sub-skill Blessed Magic to give an extra boost to the applied elemental magic. My danger awareness was giving signals that Jaune was out to kill and I wasn't taking my chances
I was proven correct as Jaune took a more aggressive approach this time around. Instantaneously, she appeared right in front of me at great acceleration. The sudden halt of her movement from me stopping her attack with my pan created a destructive shockwave
The spatial properties and its laws were shattered with the radius of the shockwave
I decided to take this up int the air for a little bit more room to maneuver and Jaune followed suit. Across the sky, far beyond the horizon, space and reality cracked, broke down and shattered completely each time our weapons collided against eachother
The gravity was permanently distorted and unbalanced
Reality was sliced and diced into oblivion from the destruction
Throughout it, Jaune was secretly planting insanely compressed abyss cores in large masses while keeping me too busy to notice. In spite of that, Yagami was easily able to detect and notify me.
Jaune had something in mind
I stood my ground for a severely long while, Jaune was definitely a fighter that is built to last with how her magicules capacity proven to truly be massive. To not only aggressively fight while maintaining a high density nuclear magic coating but to also summon what seems to be an endless supply of abyss cores
Eventually, both us settled down for a moment after an eternity of clashes
Jaune kept herself composed and confident given what she thought had been kept hidden from me
Keeping her unwavering stare upon me, Jaune reached out her fist only to form a thumbs up
Jaune: I dig ya
I was taken aback from this sudden mood swing. Just one moment she was out for my own head, now she seems completely relax and is even giving me a thumbs up of approval
Kaijuno: I don't follow. Could you elaborate on what you mean?
Jaune: I meant you surpassed my interest. Initially, you were interesting enough that I wanted continue our match but I'd be lying if I say I haven't grown fond of you. It's relieving to have an opponent to freely play rough with
Kaijuno: What makes me special? Don't you literally fight against Leon everyday? And it's not you're the only primordial, I'm sure purple and white would also be more your speed
Jaune: Don't get me started on them. I only attack Leon everyday to piss him off for stopping me from obtaining physical body to inhabit in the past. Otherwise, Leon is total buzz kill of an opponent, he just arrives at the scene acts annoyed and swats me away like I'm some pest, it's basically one and done. It doesn't help the he lives in the Cardinal World so I can't spread my wings as I could here in the demon realm.
As for the other primordials, a pain in the ass and a half is what they are. Get this, Violet screwed up obtaining a body TWICE in the last few years and still expect us to take her seriously. Who is she convincing that she still has any dignity!?
Oh and Blanc? Easily one of the most prideful and arrogant beings I've known, maybe more prideful than Guy. She acts all high and mighty when she basically just sit on her butt all day and drink wine
We keep getting in the way of eachother's goal to obtain a proper vessel to inhabit. Even without Leon, would've gotten a body by now if it weren't for those two
You're basically the only one that I can let loose against and not royally piss me off
Thinking that getting the fondness of a primordial is a once in a life achievement. I figured to finally wrap this up. If she's willing to admit she is fond of me, maybe I can settle this peacefully without fighting any further.
I even had a special finisher move for Jaune but honestly I had more than a day's worth of intense violence and I feel a bit worn out and only desire to get this over with already.
I decided to shoot my shot
Kaijuno: So you're fond of me? In that case, how about becoming my subordinate? I'm sure it would beat working for Diablo
Jaune didn't say anything in response. Infact that relaxed smile she had before was twisted into a devilish smirk fitting for a demon. Then she rotated her hand giving a thumbs up to now form a thumbs down, making it clear she wasn't submitting that easily
It was then that I gotten an urgent sense of danger followed with Yagami warning me of high level of nuclear magic about to be used
Just then, all the compressed abyss cores above us have shifted and formed into an entire sky of singularities to then a sky of black holes. The gravitational force became absolutely chaotic
Jaune has unleashed Gravity Collapse
Everything has become an unimaginable level of distortion, far surpassing the destruction that came before
Any remains of a surface that was the crater had collapsed and scattered all over. Some fragments crumbled like dust or merged into clusters, other were warped and stretched like taffy
I myself had to put on multiple measures to endure and resist this world incomprehensible chaos. Yagami managed gravity manipulation to push against and resist the gravitational push.
I applied multi-layer barrier to ensure general endurance while instinctively used universal shapeshift and infinite regenerate to recover from the intense pulls and prevention from being torn apart into multiple pieces.
The best way I could describe the experience was like getting caught in a hurricane that couldn't make it's mind on which direction it intended to go
Eventually the disruption finally subdued and the pressure surrounding me finally faded, much to my relief. I had focus on infinite regeneration once the intensity withered as I still felt like I was torn to shreds by the gravity collapse. By the end of my recovery, I ended using a concerning amount of magicules just to prevent myself from getting ripped apart from the gravity chaos
But much to my dismay as I was already feeling worn out, her attack was only half finished. Just as the flow was slowing doing, an intense flow of energy suddenly bursted outwards of the singularities outward of the singularities that were the center of the black holes.
It's an explosion of light that resembles a supernova
Seeing as now there was an upcoming explosion that could tore galaxies to shreds, I resorted to using Monster King Gojira to consume all of the masses of released energy heading right towards me. I needed a hearty meal after all happened in this whole ordeal
And consumed it did as the raging fangs of a beast that was the Ultimate skill, devoured the light as if it was a black hole itself
Even the fury of exploding stars that was aiming to annihilate me only ended up falling prey to the merciless fangs of the Monster King. Thanks to the consumption of the attack, my own magicule supply of was filled enough so I didn't have to worry about running out anymore
As for the one who set off the attack, it turned she had the gravity collapse contained in a barrier on her own creation. It was because she kept it within a limited radius to prevent herself caught within her own attack
Who was likely held a twisted smirk for most of it now holds an expression of astonishment as she was staring from above. What was a devastating attack that she thought for sure would finish off her opponent had suddenly disappeared along with her opponent in far better conditions than expected, especially after what had already occurred
She put a lot into that gravity collapse only for the annihilation to extinguish at the most exciting part
In spite of her previous smug attitude and to simply show off, I cross my arms and use wind magic to lift my robe behind me, all while I stoically stared back at her
The bewildered Jaune shook off her astonishment and demanded what the hell I just did. A newbie demon lord wouldn't be the type being to suddenly stop her attack let alone survive it mostly unscathed. I could see the likes of Carrion, Frey and Clayman not surviving. I believe a good reason why I hadn't incinerated was due to slimes already being naturally regenerative on top of evolving into a spiritual being
Feeling replenished, I regained the mood for theatrics. Returning a smug expression back at her, I have my response
Kaijuno: Was it not obvious from the start? I may be a demon lord, but that isn't all who I am
I am the one who is on top of the food chain!
I am the King!
I am the Devil!
I conjured a large cluster of abyss cores above my hand. During our sword clash, Yagami analyzed and copied the compression process that Jaune performed in secret. Originally what I had intended to be my finishing move was a lot more simplistic but because of this analysis, it opened the opportunity for me to perform gravity collapse especially since I already have access to nuclear magic
Unlike the abyss that were spread out previously in the air, the abyss cores I held were compressing against eachother to merge into a lone but massive singularity. Jaune know full well what I was performing, was setting off to get as far away as she could.
After what she put me through, I wasn't gonna accept her fleeing away. While the the gravitational pull was still calm enough to push through, I used universal shapeshift to stretch my arm towards her direction.
To her distraught, I was able to grab onto her leg before she could escape. Just when I had firm grip on Jaune, the singularity transformed into a black hole that pulled us both into it
Jaune made a clear effort to resist against the pulling, however she seemed to have drained herself of most of her strength from the gravity collapse.
I was worried for a good chunk of our fight as Jaune was mostly reliant on her sword arts and only relied on nuclear magic to strengthen her blade rather than spamming it. But it's shown she used most of her capacity to preform that mass of gravity collapse
Most likely the case from the instance that I was present for was that Jaune really only intended to send petty attacks upon Leon's domain just to piss him off all while under the restriction of maintaining a temporary material body.
Without that restriction and with more killing intent, Jaune revealed that she can be capable of some horrifying magic. She truly lived up to the title of Primordial
But here, she was reckless. She put most of her chips in one bet, and ended up high and dry
As the both us were pulled into the center of the black, my arms shorten back to the normal length. Unlike before where I was just pulling her towards me, now I trapped her in the tight embrace of my arms and I was refusing to let her go
Jaune continued to struggle even when we both caught inside the blackhole. I see the battle as good as done by this point. Not only did I tanked a lethal attack from a primordial of all beings but now I have that same primordial at my mercy as I'm throwing her specialty right back at her
This rush of excitement didn't just make me feel smug. I formed a maniacal grin from what I was actually accomplishing
After trying to shake me, Jaune only stared right back at as both of our faces were right in front of eachother
Seeing as I now have her full attention, I decided to finish what I was previously saying. Infact what I had in mind is unironically sounds like the best thing to say to a combustion prone opponent that Jaune is
Kaijuno: But do you know what else I am?
It's nerdy and honestly, might even be cringy as well.
I
AM
But despite that, I know I won't really have another opportunity to pulled this off so I might as well do it now
Atomic
Light was all that could be seen and light it only was until there was void when the calm came.
The primordial yellow was nowhere to be seen. No fragments of what was once a surface erased completely.
All there was in the void was merely a raven black slime floating within the abyss in a dormant state as it succumbed to it's exhaustion. Leaving the later results of the battle to be left uncertain
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Back at Tempest, Rimuru is performing their daily routine of going through bloated piles of paperwork that they wished they didn't have to do
In the middle of this, the tsundere otaku dragon Veldora barged into the office to ask more more shone jump volumes
Rimuru seemed annoyed that Veldora interruption but had still gave the volumes without much contest. Infact the interruption seemed to be the least of the slimes concern
Noticing this intense focus, Veldora had asked what was up. It wasn't out of the blue for Rimuru to be frustrated at his mountain of work this time there was an expression of contemplation
It was revealed that they had recently recieved a letter from the council of the west that they have approved to offer Tempest an invitation to their next meeting.
Initially this sounded great, except upon a closer look on the words chosen in the letter
The lettering of the invitation made it seem like they were specifically asking for Kaijuno's precense in the next meeting and seemed to purposely exclude the mention of Rimuru which left the blue Hawaii colored slime with a brow raised
It seems that council specifically wants Kaijuno to attend rather than the both of them. It looked to be fishy that they want solely one of the ruler instead of being open for both
Veldora could see this was a trap thanks to the analytical skills of Investigation King Faust. But even if this was the case, they were short of leeway
While Rimuru normally wouldn't have complained about getting some workload other of their shoulders, Kaijuno isn't someone they would have in mind for this type of job
Despite being proclaimed by the citizens as one of the Twin Rulers along with having the same respect from their people, Kaijuno is not really suited for this type of job.
Politics is something that Rimuru is the one to handle while Kaijuno's occupation is a student. And especially with the concerning behavior Kaijuno presented during the events of the harvest festival and Walpurgis
But Veldora brushed that off as it was a tough time for everyone back then and Kaijuno had likely cooled off by now
But still Rimuru would've rather join Kaijuno in the meeting but there comes another issue
As of recently there has been a rising surge of merchants visiting and moving to Tempest due to the success of the founder's festival. Thanks to this along with the opening of the Labyrinth, there has been a rise of job opening but the growth of these openings have been reaching a concerning rate
If it keeps going at this rate, they'll eventually reach of worker shortage. With the supply of workers not reaching the demand of workloads, everyone is starting to get stretched thin including Rimuru
Given all the paperwork they have back up, there wasn't a likely chance for Rimuru to be able to finish by the time of the meeting is scheduled
Since Kaijuno explicitly was the one to be invited in the letter, Rimuru doesn't have the excuse that this meeting was a mandatory time away from his workload and given how everyone else is already heavily busy, the likes of Cameilla would most likely wouldn't be convinced and would insist that Rimuru continue focusing on the endless piles of paperwork
After further contemplation, it was decided Kaijuno would be accompanied by the likes of Benjamin, Leonardo, and Cameilla
There was consideration to have Vesta come along to as he helped Rimuru in the past with establishing a diplomatic relationship with Blumund in more fair terms for both parties but with the concern of it being a trap, it was preferable to avoid risking Vesta getting caught in the crossfire.
So instead Cameilla can cover any diplomatic talks as she had been under the teachings of Vesta. Benjamin will work as a frontal Bodyguard for Kaijuno while Leonardo will cover for any surrounding dangers
Veldora offered to come along in the case if it was a trap but was shot down as unlike with Walpurgis, his presence wouldn't really be beneficial. Also the idea of the storm dragon visiting another kingdom sounds as bad as it sounds and would be a risk to Tempest's reputation when they just reached an all time high
This is also the case for some like Lavandra and Gobta or that others are simply too busy to attend like Geld and Rigurd
Rimuru had also recieved word from Hinata the she will be attending the meeting too which helps relieve Rimuru's concern as Hinata can be trusted to make sure Kaijuno doesn't do anything ridiculous in the meeting given her stoic nature
As for the man of the upcoming hour, there was the matter in regards to him currently not being in Tempest
It was best to have Kaijuno take break from his venture in the demon realm rather than waiting for him to return by his own time
But when they sent a thought communication, there was no response for a concerning amount of time. Thinking that something had happened, an urgent message was sent to Diablo who responded in excitement
There was instant question if anything had happened to which Diablo had denied anything to be concerned only to asked about Kaijuno's whereabouts as he wasn't responding
Diablo had stated that Kaijuno is in a dormant state after exhausting himself to the desperate gratitude of Rimuru.
Rimuru then let Diablo know that Kaijuno will need to return back to Tempest to which the black butler said will be done so.
After confirming what was needed, the call was cut leaving the primordial black in a brief displeasure of no longer speaking to their master . . . Only to then be jumping around in excitement and joy
Finally after all the time in this journey, he'll be relieved of the annoyance that was Kaijuno.
For Diablo, he only intended to to scout out his fellow primordials with seeing any other horde of demons being pointless for his attention which is the opposite for Kaijuno who seemed set to collect as many demons as he can find in spite of their age or evolutionary stage
Diablo would've whole heartily abandoned Kaijuno if it were up to him but due the deal between them along with officially being paired up together by Rimuru, Diablo can't afford to split paths for his personal convenience as confirmed when Rimuru asked about Kaijuno's whereabouts
As loyal Diablo was to Rimuru, he didn't really have much patience for anyone disobedient and troublesome which Kaijuno fits in perfectly for Diablo.
Unfortunately as much as he would like to use severe disciplinary methods to get Kaijuno in line for what Diablo considers to be the only priority, he doesn't consider himself to posses the authority to do so. It wasn't because he have much respect for Kaijuno but it was an hierarchy issue, as Kaijuno and Rimuru are labeled side by side as the authority of Twin Rulers which his master has not denied being the case
So begrudgingly, Diablo endured each side quest Kaijuno randomly pursues as any belittlement to Kaijuno's authority would be a secondhand belittlement to Rimuru's authority, something that Diablo isn't willing to risk
Even without this journey, Diablo wasn't impressed by Kaijuno. At best Kaijuno was merely a desperate imitation to the perfection that was his master. He also wasn't pleased that Kaijuno wears a replica of shizue's mask, one of the few people he ever shown interest and respect
All in all, Kaijuno is simply weight that Diablo was all the more willing to drop the moment he had the opportunity to do so
For the time being, the primordial of the black lineage simply stood, waiting in silence for the King to awaken and be unleashed from it's slumber