Before Yoh Asakura ever enters the Shaman Fight tournament, this collection of standalone stories traces what shaped him and the people around him: his twin brother Hao Asakura, his fiancée Anna Kyoyama, the fighter Ren Tao and others. Each chapter stands on its own rather than building toward a single arc, filling in the childhoods and training years the main series only glances at. Zero was written after Shaman King's main story had already concluded, and stays a set of side stories to that run.