Hikari Hoshino, a struggling actress, discovers that the president of her talent agency has accumulated a massive debt with a vicious yakuza syndicate known as the Kan-gumi, all in a misguided attempt to promote her career. Desperate to buy time for repayment, Hikari visits the Kan-gumi headquarters, where she comes face to face with Jin Kan, the group's young and formidable acting head. Despite the intimidating circumstances, Jin is immediately captivated by Hikari, and he proposes an unusual arrangement: the collateral for the debt will be pure love. What begins as a transactional standoff quickly evolves into an intense, volatile romance between a mad dog yakuza and a down-on-her-luck actress.

The narrative follows Hikari and Jin as they navigate their deepening feelings amid the dangers of the underworld. Jin launches an overwhelming and sincere romantic pursuit, and though Hikari initially remains wary of his aggressive personality, she gradually finds herself drawn to his genuine nature and unexpected tenderness. Their growing relationship is tested when Hikari's younger brother Yutaka arrives from the countryside and inserts himself into the situation, complicating the couple's dynamic. At the same time, a series of orchestrated attacks target the Kan-gumi's top executives, sending the organization into turmoil. The mastermind behind the assaults is revealed to be Ken Ryuzo, the head of a rival syndicate called the Ken-gumi. In a bid to weaken the Kan-gumi from within, Ryuzo takes his own daughter hostage and forces his son-in-law, a man named Omagari, to act as a spy. Torn between loyalty to his family and his conscience, Omagari eventually decides to confront the Ken-gumi alone. The series concludes with a happy, peaceful resolution as the threats are neutralized and Hikari and Jin solidify their bond.