When Raku Ichijou was young, he made a heartfelt promise to his childhood friend that if they were to meet again, they would marry each other. Ten years have passed since that fateful day, leaving Raku's memory of her faded. But he still holds a relic of their relationship together—a locked pendant, which his childhood friend holds the key to. He hopes to reunite with her one day, despite not remembering what she looks like.

Now a first-year student at Bonyari High School, Raku attempts to live a normal life, dreaming of becoming a public servant and marrying his crush Kosaki Onodera. However, this isn't as easy as it seems, as he is the unwilling heir to a large yakuza family, and Raku can't escape from his duties when the American Bee Hive gang wages war on his family's turf. In order to forge peace between the two feuding families, Raku is forced into a fake romantic relationship with Chitoge Kirisaki, the beautiful daughter of the Bee Hive's leader. The two quickly come to hate each other, but have to learn to live together and pretend to be deeply in love in order to keep their families at bay.

However, Raku's quest for the key to his pendant isn't becoming easier as more girls—who were all involved with his pendant in some way—enter his life. Join Raku as he juggles his false relationship, maintains the balance between warring families, and unravels the identity of the girl who will unlock his heart.