Based on a Japanese manga series written and illustrated by Takeshi Konomi. The manga was serialized in Shueisha's Weekly Shounen Jump from July 1999 to March 2008, with its chapters collected in 42 tankobon volumes.
On April 2, 2021, Funimation obtained licensing rights to the series and announced a new dub was in the works.
On April 24, 2007, Viz Media released the first DVD box set in the United States. An additional three box sets have been released since January 15, 2008. However, these four sets only contain 50 of the 178 episodes.