History's Strongest Disciple Kenichi Vol. 37

Ragnarok member Thor plans to develop his Sumo
wrestling into a practical martial art. Loki plots against Odin by
planning to replace him with Berserker. Niijima reveals he knows what
Kenichi's death blow is, a combination of moves from every martial art
Kenichi is learning, (a Karate punch, followed by a Muay Thai knee
strike, followed by a Chinese head-butt and finished by a Judo throwing
move). Niijima suggests Kenichi go on the offensive by attacking a
Ragnarok member. Kenichi asks his masters advice on being the one to
instigate violence. The masters are happy Kenichi has matured enough to
ask such a question but insist that finding his own answer is an
important part of his training. Kenichi decides it is acceptable to
attack as long as he fights with honour. Kenichi and Shinpaku Alliance
head to an underground fighting arena run by Thor where Kenichi
challenges him to a match. If Kenichi wins, Thor must leave Ragnarok, if
Thor wins Kenichi must become Thor's disciple and help him make Sumo
into a real martial art. They enter a ring that has been dug into the
ground so fighters cannot be thrown out, and instead must be beaten
unconscious. Due to his thick muscles Kenichi is unable to hurt Thor
with his normal attacks and gets hit by him several times. Kenichi uses
his death blow on Thor but struggles to throw such a heavy opponent.
Somehow Kenichi finds the strength to lift Thor completely off the
ground and throw him out of the hole, which counts as Thor leaving the
ring and being defeated. As an honourable martial artist Thor admits
defeat and swears to leave Ragnarok and give up on his dreams to develop
Sumo wrestling, though Kenichi points out he only asked Thor to leave
Ragnarok and encourages him to keep following his dream.