From Kodansha:
Shamans possess mysterious powers that allow them to commune with gods, spirits, and even the dead. High schooler Manta Oyamada doesn't know much about them, but that changes fast when his class welcomes a new transfer student from remote Izumo: Yoh Asakura, a shaman in training! Although he may just be starting out, Yoh’s dream is a big one: to become the Shaman King, the one and only shaman who may commune with the Great Spirit and help remake the world for the better. But the road to this pinnacle of spiritual power runs through the Shaman Fight: a gauntlet of battles with rival mediums who call forth dizzying powers from the world of the dead in their own bids for the crown. It’d be nice if Yoh had a little more time to train and mature but the Shaman Fight is only held once every 500 years, so he’s going to have to grow up fast.

Official English

The serialization ended in 2002 after 32 volumes leaving the story unresolved. Shueisha then released the Kanzen-ban (full version) and Renka-ban (cheap version) versions with additional pages and side stories resolving the plot.
The epilogue Day after Maize was added to volume 35 in 2021.
Kodansha acquired the rights in 2017 and used the Kanketsu-ban edition in digital and print.