Shaman King is a 285 chapter, 32 volume manga and 64 episode anime series created by Hiroyuki Takei.
The manga started in Shueisha's Weekly Shōnen Jump in Japan, which lead into the creation of the anime.
The anime starts off following the events of the manga for about half the series and then slowly moves into its own plot.
You can see more about the manga at their English site here.
And you can learn more about the anime series at JETIX's Shaman King website here.
