Obi o Gyuttone!

is a popular judo manga in Japan. Judo is a Japanese martial art, which is widely loved by the Japanese.

Judo has an image of dirty and hard training, so Judo manga used to have a lot of these scenes. "Tighten your black belt hard!" is a new type of Judo manga which draws Judo "clean".

This manga was written between 1988 and 1997 by Katsutoshi Kawai, a new writer at that time; Katsutoshi Kawai is now writing other manga.

The hero is Takumi Kogawa, a high school student. The main characters are his four friends, his girlfriend, and his girlfriend's friend. The story begins with these characters meeting together and making a judo club that didn't exist at their school.

Takumi Kogawa has a model, Toshihiko Koga, a popular Judo player.