Seichiro Toba serves as headmaster of Kyowa Institute, an institution founded by Sukaza Ryudo, grandfather of the four Ryudo brothers. He attained this position by marrying Saeko Toba, Sukaza Ryudo's daughter and aunt to the Ryudo brothers. His primary motivations are financial profit and political advancement, specifically targeting the role of head of education in Tokyo. To achieve these career goals, he employs unethical methods, including deceiving family members.

Significant animosity defines Seichiro's family relationships. His daughter, Matsuri Toba, exhibits profound contempt and embarrassment towards him. The four Ryudo brothers intensely dislike him, largely because his actions cost Hajime Ryudo, the eldest brother, his History teaching position at Kyowa College. In contrast, the brothers hold considerable respect and affection for his wife, Saeko. Saeko endures his behavior, and it is implied Seichiro married her primarily to gain control of the college rather than out of genuine affection.

This character appears in Yoshiki Tanaka's original novel series, the foundation of the narrative, and consistently in the 12-episode original video animation adaptation. Information about his presence in Clamp or Kōji Megumi's spin-off manga adaptations is unavailable.