How did yamauchi became the strongest in cote?

The way that yamauchi became the strongest in cote, is he came from the blackroom, the experience of his is the most brutally in all of existence.

He was isolated in the blackrooms at the age of 6, after he woke up he realized that he was in a box of glass with full of kids, the instructor present them where they are and what is allowed, not allowed, and what contains in this vicinity.

After a single month one of the prime minister who is in charge in the blackrooms were astonished by his talent.

After 3 years that event has ended he picked 5 to participate and one of them is yamauchi,

yamauchi were experienced at martial arts, combats for 3 years, but it didn't just end there.

After they got participated 5 of them were move in a deeper level, testing their strength most likely anyone there didn't pass except for yamauchi, yamauchi completed the level within a single scratch

The levels were:

1 • Wood

2 • Boulder

3 • Bricks

4 • Metal

5 • Steel

Although, Yamauchi didn't even tried he mostly calculated his strength after the 2 kids after him were done he uses the calculations and conquer the concepts of his limit and it worked everyone that is around him was astonished, the prime minister felt a presence that is negative and positive at the same time.