Unwol

He was the master of Chun-Woo Han and Ryuji. After achieving the Black Origin Threshold the Martial Arts Alliance banished him to a life of meditation and solitude in a cave while he tried to figure out a way to solve the problem of this technique. He was always calm and composed, and did not hold a grudge against the elders that exiled him. Despite almost never showing emotions, he is very caring as he expelled Ryuji as a disciple and killed himself to protect both Ryuji and Chun-Woo Han respectively.

(Source: The Breaker Wikia)