A woman who runs a care helper company with her husband receives an application from a new client. His name is Saito Osamu... In fact, her father was the boss of the Sakaguchi-gumi gang, and was killed by Saito Osamu, the boss of the Saito-gumi, during a conflict at that time. Her memories of that day come back to her, and she hides her true identity and approaches Saito in order to get revenge, but the person she meets is completely different from what she imagined: a kind and fragile old man...