Tetsu Takemoto runs the small Osaka izakaya Horumon in Nishi-Hagi-cho, Nishinari-ku, relying on his daughter Chie to manage it while he largely avoids work. Defined by laziness, gambling addiction, and financial recklessness, he frequently borrows money from his parents and accumulates debts with local figures like the yakuza Shachou. Though occasionally well-meaning, Tetsu consistently prioritizes his own desires over family stability. His volatile, immature personality leads to physical confrontations and public disturbances, and he shows open hostility toward his separated wife, Yoshie, hindering reconciliation. Their marriage was initially arranged by Tetsu's former homeroom teacher, Kankotsu Hanai, whose son Wataru later becomes Chie's teacher and attempts mediation. Tetsu's parents regularly admonish him for neglecting Chie and mismanaging family resources, treating the adult like an irresponsible child.

Tetsu's unemployment persists until Shachou, now a restaurateur, hires him as a security guard following the death of Shachou's cat, Antonio. This opportunity arises indirectly from conflicts involving Chie's cat, Kotetsu, who defeats Antonio and later spares Antonio Jr. during a revenge confrontation. While resenting Kotetsu's aggression, Tetsu benefits from the cat's role in resolving his debt issues with Shachou. His relationship with Chie remains contentious, marked by mutual frustration, though she defends him when necessary and persistently seeks to reunite the family. Her efforts lead to a tentative reconciliation, culminating in Yoshie moving back in. Their strained relationship shows slow improvement through shared experiences like a family amusement park outing.

Tetsu speaks in the Osaka dialect, reflecting his regional identity and working-class background. His character development is minimal across the series, maintaining his flawed traits as a central source of familial tension. The story's episodic nature and running gag about Chie's perpetual fifth-grade status imply a static timeline, limiting significant long-term growth. Tetsu's role primarily serves as a catalyst for comedic and dramatic situations centered on family dysfunction and resilience within Osaka's cultural context.