Mr. Happy is the personification of Kazuma Kanno's penis, appearing as an energetic, talking sea lion in the adult animated OVA series. Kazuma, the successor to his family's declining sex-based entertainment enterprise, receives a mission from his father: to study sexual dynamics and intercourse across various environments to revitalize the business. This mission specifically requires Kazuma to bring women to climax without achieving orgasm himself.

Mr. Happy accompanies Kazuma on this journey, acting as his direct advisor during encounters. He provides real-time guidance and commentary on sexual techniques and strategies. Kazuma's research involves visiting highly sought-after geishas across Japan, including Manchiyo from Atami, aiming to refine his understanding of female pleasure under the imposed constraint.

Mr. Happy embodies Kazuma's sexual function and confidence. His dialogue and interactions directly reflect Kazuma's psychological state and challenges. Through his presence, Mr. Happy facilitates the exploration of the sexual themes central to Kazuma's development and the family business objectives.