FIRST THINGS first.
The culprit who pushed Shin Jina down the stairs was the coach of Shin Jina's top rival in the upcoming Taekwondo competition.
And the top rival in question is a kid from a rival school, too.
Anyway, Coach Park Sungmin, a former Taekwondo national athlete, was the culprit.
Apparently, the coach was threatened by the rival's family that if their kid lost to Shin Jina again, then they wouldn't only fire him, but they would also do everything in their power to shut down Coach Park Sungmin's Taekwondo academy.
Desperate and stressed from the rival family's continuous harassment, Coach Park Sungmin lost his mind. He sneaked into the school, which he was able to do as a former P.E. teacher there, and did what he had done to Shin Jina.
Of course, Yang Iljun— the school principal— was extremely furious.
