GTO: Great Teacher OnizukaGTO: Great Teacher Onizuka.

Great Teacher Onizuka, abbreviated as GTO, is a Japanese manga series written and illustrated by Tōru Fujisawa. It was originally serialized in Kodansha's shōnen manga magazine Weekly Shōnen Magazine from January 1997 to February 2002, with its chapters collected in 25 tankōbon volumes. The story focuses on 22-year-old ex-bōsōzoku member Eikichi Onizuka, who becomes a teacher at a private middle school, Holy Forest Academy, in Tokyo, Japan.