"From now on, is it okay for me to have an ‘adult relationship’ with you, Young Lady?" Yui Amagi is the daughter of a yakuza family who longs for a "normal life." Her dream of living on her own finally comes true… or so she thought. But her assigned bodyguard—who also happens to be her fiancé—Ichika Izumo, the Wakagashira (Underboss) of the Amagi group, insists that "it’s only natural for me to be here," while smoking a cigarette as if he owns the place. Yui doesn’t actually dislike Ichika (in fact, she secretly likes him), but she doesn’t want a romance arranged by her parents. Without realizing her own feelings, she decides to spite him by joining a group blind date. However, once the party starts, she feels completely out of place and ends up depressed. To make matters worse, one of the men there takes advantage of her vulnerability and tries to take her to a hotel…!? "You dare join a group date when you already have me, your fiancé?" An impatient yandere Underboss × a stubborn young lady, caught in an overly intense and sweet “awakening cohabitation love story”… ♪