They adapt the first through eleventh volumes of the manga over twenty-four episodes. The remaining two episodes follow an original storyline not found in the manga written by Yagi.
Based on the shounen manga series written and illustrated by Norihiro Yagi. It debuted in Shueisha's Shounen manga magazine Monthly Shounen Jump in June 2001, where it continued until the magazine was shut down in June 2007. The series was transferred to the newly launched Jump Square, serialized from November 2007 to October 2014. Its chapters were collected in 27 tankobon volumes.