Kou Ichinomiya, a 22-year-old university student and heir to the Ichinomiya corporation, lived entirely by the strict family motto "never be indebted to anyone," instilled by his father Seki and symbolized by a passed-down tie. Despite his elite status, he independently managed companies, owned a luxury apartment, earned over 800 million yen, and funded his own education. He never knew his mother.

A pivotal moment occurred when delinquents stole his pants and threw them onto the Arakawa River bridge. Attempting retrieval, Kou fell in and nearly drowned. He was rescued by Nino, a girl living under the bridge who claimed to be from Venus. Bound by his creed to repay the life debt and finding Nino refusing money, Kou agreed to her demand to "experience love" with her. He abandoned his former life to become her boyfriend and live under the bridge.

The self-proclaimed Kappa leader of this riverside community renamed him "Recruit," often shortened to "Riku," marking his newcomer status. Kou disliked the name but accepted it after rejecting the alternative "Naitei Toreta." Adapting to communal life, he built a living space on a bridge pillar and took on the role of teacher for local children. The eccentric residents frequently provoked him, triggering severe asthma attacks—a family trait worsened by stress.

Kou has black hair, brown eyes, stands 172 cm (5'8") tall, and weighs approximately 55-56 kg (123 lb). His blood type is A and his zodiac sign is Virgo. Though academically and financially accomplished, including proficiency in violin, his romantic inexperience led him to rely on manga for relationship guidance. Interacting with Nino and the community gradually reshaped his worldview, forcing a balance between his ingrained principles and new relationships. This new life brought conflict when his father later attempted to reclaim him and redevelop the riverbank.