Tetsuta and Aya are two siblings who lost their mother very early in their lives. Despite being loving and devoted, their father has since buried himself in work and hardly ever spends time with them. Tetsuta is fully accustomed to looking after his younger sister and cooking for the family, so he vehemently opposes his father's suggestion of bringing in a helper to tend to matters around the house and care for them. But his attitude changes the moment he meets this beautiful and kind-hearted housekeeper…

Sachie Wakamura just lost her mother, and her estranged grandfather has shown up to take care of her. The only problem is that Grandpa is the head of a yakuza gang! Sachie tries to continue living her normal life, but she can't run far since Rakuto, one of the most popular guys in school, is part of her grandfather's gang and her new protector. Soon, Sachie finds herself falling for her bodyguard. But she's the granddaughter of Rakuto's boss, so he can never show his feelings for her. Can Sachie find a way to fit into her new family and seize her chance at romance?