Souichirou Amano is the biological father of Nagi Umino and adoptive father of Erika Amano, a situation stemming from a hospital mix-up at birth that caused the children to be raised by each other's biological families. A wealthy hotel tycoon owning a prominent chain, he is married to television producer Ritsuko Amano. He possesses dark brown hair, black eyes, and shares physical resemblances with his biological son, Nagi.
His personality appears affable and understanding, yet underlying traits reveal a calculating and manipulative nature. Souichirou orchestrates an arranged marriage between Nagi and Erika, intending their cohabitation to foster romantic feelings. This plan aims to ensure both children remain connected to their biological and adoptive families, partly motivated by a desire to avoid losing the children they raised. He demonstrates evasiveness when confronted about sensitive topics, such as the existence of Nagi's biological older brother, Sousuke Amano, redirecting conversations to avoid direct answers.
Souichirou's relationship with Nagi is complex, marked by secrecy regarding their biological connection and Sousuke. Sousuke disappeared before the arranged marriage events and later resurfaces working for Dojima Hotels with a stated motive to "destroy the Amano clan," indicating unresolved familial strife. Souichirou's avoidance of this topic suggests deeper conflicts within the family dynamic.
His role involves influencing major decisions, such as transferring Erika to Nagi's school after disciplinary issues and enforcing the cohabitation arrangement. Despite his manipulative tendencies, his actions are framed as protective, aiming to unify the family, encapsulated by the quote: "I'll protect you, even if I have to break the world to do it." This reflects his driven, morally ambiguous approach to safeguarding his family's interests.
Character development reveals ongoing tensions, particularly regarding Sousuke's antagonistic motives, though Souichirou's direct involvement or responses to this threat are not elaborated.