Gamaran

Unabara Domain—home to nightmarishly strong students and masters of martial arts of all kinds. The lord of the Unabara has decided that whichever of his sons discovers the strongest martial arts style will be his heir, but when 28th son Naoyoshi Washizu decides on Ogama-style practitioner Gama Kurogane, son of notorious father and scion of a "weak" style, to represent him, the odds seem bleak. But between Naoyoshi's determination and Gama's hard-earned strength, they may yet come out on top!

(Source: Kodansha USA)