The night slowly passed, and the sea became calm again.
Soft light from the morning sun spread across the water.
Everyone felt tired… but safe.
Kichy Rabbit stayed close to Miku.
"You really saved me," he said quietly.
Miku smiled. "Next time, don't fall."
Peggy looked ahead.
Far in the distance, something huge appeared.
Tall… dark… and rising out of the sea.
"What is that?" Kichy asked.
Pinky Pig narrowed her eyes.
"That… is the North Sea Mountain," she said.
As the ship moved closer, they saw it clearly.
A giant rocky mountain stood in the middle of the sea. Around it, the water was deep and still… almost too still.
"There is a lagoon beneath it," Pinky said.
Peggy took out the map.
"But we already know the way," she said.
Pinky shook her head.
"Not completely," she replied.
She pointed to a hidden mark on the map.
"There is a locked path near Sandy Island," she said. "To read the full map… we need a key."
"Where is the key?" Miku asked.
Pinky looked toward the dark water.
"Under the lagoon."
Everyone went silent.
"The lagoon is deep," Pinky continued. "Cold… and strange. Not many who go down… come back the same."
Kichy stepped back. "Then we shouldn't go!"
"But we need the medicine," Peggy said softly.
They all looked at each other.
Before anyone else could speak…
"I'll go."
It was Chikku.
Peggy turned quickly. "No, it's too dangerous."
Chikku shook his head.
"You all saved me when I had nothing," he said. "Now it's my turn."
Miku stepped forward. "I'll come with you."
Chikku smiled slightly. "This is something I have to do."
Kichy's ears dropped. "Be careful…"
Chikku nodded.
A rope was tied around him.
He stood at the edge of the ship and looked at the water below.
It was dark.
Too dark.
He took a deep breath…
…and jumped.
Splash.
The cold water surrounded him instantly.
He swam downward.
The light from above slowly faded.
Everything became quiet.
Strange shapes appeared around him—rocks, plants, and shadows moving slowly.
Then…
He saw it.
A small glowing object resting between two stones.
"The key…" he whispered.
He swam closer and reached for it.
The moment his hand touched it—
The water around him changed.
A soft glow spread through the lagoon.
Something unseen moved around him.
A deep, quiet voice echoed.
"You have taken what belongs to the lagoon…"
Chikku looked around, scared.
"I… I need it," he said. "To save someone."
There was a long silence.
Then the voice returned.
"Then you must carry a part of this place… forever."
The light grew brighter.
Chikku felt something change inside him.
The water no longer felt heavy.
He could breathe.
His body felt… different.
But he held the key tightly.
"I accept," he said.
The glow slowly faded.
Above, Peggy and the others waited anxiously.
"Pull him up!" Kichy shouted.
They began pulling the rope.
Slowly… slowly…
Chikku rose from the water.
He climbed back onto the ship.
Everyone rushed toward him.
"Chikku!" Peggy said.
He looked at them… and smiled.
"I got it," he said, showing the key.
But something was different.
His eyes had a soft blue glow.
His movements were calmer… deeper… like the sea itself.
Miku looked closely. "You're not the same…"
Chikku looked at the water quietly.
"The lagoon… is with me now," he said.
Kichy whispered, "Lagoon boy…"
Peggy held his hand gently.
"You saved us," she said.
Chikku nodded.
But inside…
He knew something had changed forever.
The ship slowly moved forward again.
Now with the key.
Now with a new mystery.
And a friend…
Who belonged not just to them…
But also to the deep, silent lagoon.