Mannoko Oyamada

Mannoko is sharp, confident and fond of teasing Manta. Her age does not prevent her from behaving with considerable self-assurance, particularly when discussing technology or her place within the family company.

She is an exceptional computer user. Her father recognizes her talent and places her in charge of the Oyamada Company's software operations, though Mannoko herself finds the responsibility troublesome rather than glamorous. She is also noted for her fondness for men who wear glasses.

Her teasing has limits. When family conflicts become genuinely upsetting, Mannoko behaves much more like the young child she actually is.

Mannoko is not established as a shaman and does not possess the combat abilities used by most of the series' tournament participants.

Her exceptional ability instead lies in computing. Despite being only five, she is described as a master with computers and is placed in charge of the Oyamada Company's software department. Her technological aptitude is extraordinary even within a family whose wealth is built around electronics.

Mannoko first appears during Manta's hospitalization after his encounter with Faust VIII. She accompanies her mother when the family visits Manta and casually reveals information about Manta spending time with Yoh.

She later accompanies the family as Manta is prepared to leave for America. Manta instead chooses to run away and rejoin Yoh, demonstrating how far his experiences with shamans have pulled him away from the expectations imposed by his wealthy family.

Mannoko remains a minor figure in the original manga, primarily providing a glimpse into Manta's home life and the unusual Oyamada family.

Manta Oyamada is Mannoko's older brother. She frequently teases him, although his conflicts with their parents can visibly upset her.

Mansumi Oyamada is Mannoko's father and the head of the Oyamada Company. He recognizes her unusual computing talent and gives her responsibility within the business.

Keiko Oyamada is Mannoko's mother and accompanies her during visits to Manta.

Yoh Asakura is Manta's friend and indirectly becomes a source of conflict within the Oyamada household because Manta's parents disapprove of their son's association with a spiritualist.