Tough Gaiden: Oton

The series starring one of illegitimate children of Kiryu Miyazawa, Ryuusei Nakamura. Years after Kiibo founded the new dojo, both him and Kiryu mysteriously disappeared. Ryuusei, after losing his mother to cancer, is set to find out about his birth father and his destiny as the evil dragon’s heir, but he is not the only one.

A series dedicated to the father of Kiichi from the series Tough. This is a side story of the Tough series based around Miyazawa Seiko (Kiichi's father) and his brother Kiryu. Much of the same elements of Tough can be found here such as Mixed Martial Arts Fighting and alot of Violence.