The the tale of Hao Asakura, a Shaman King character, as a child 1000 years ago. In this original incarnation, his name is Asaha Douji. He was named after his mother, Asano Ha, who was killed by humans for being a yokai who could see and speak with demons. After his mother's death, Asaha is left with no home and no family. He meets and befriends a demon named Ohachiyo who renames him Mappa Douji (Demon Child), to avoid confusion between his and his mother's similar names, as the kanji could be pronounced both ways. Ohachiyo teaches Mappa Douji many things, and towards the end of the story he gives Mappa Douji the demonic power of reading minds, the beginning of Hao's powerfully and dangerously gifted mind.

It is not told in this story, but in the main Shaman King manga, Hao later becomes an onmyōji, which is a hint that Hao's fictional life may be based on the Japanese legend of Abe no Seimei, a famous onmyōji whose mother was also rumoured to be a yokai.

"Mappa Doiji II" (Parts 1 & 2) are part of Shaman King Zero, chapters 6 & 7.