His rule: No sexual relations until age 18! Her rule: No rules.
Free—spirited Yuri Hasegawa and straitlaced Keiichiro Katsuragi have fallen in love. But his elite political family—producing a line of prime ministers—does not allow male descendants to engage in any sexual relations until they are 18. Can the physically affectionate Yuri and rule—abiding Keiichiro keep their relationship strictly chaste?
The couple has finally headed off on their romantic school trip. But Yuri gets ahead of herself and gives Keiichiro a kiss on the forehead, which suddenly triggers the Katsuragis into high—alert mode! Keiichiro’s older brother, Shotaro, arrives on the scene. At first the two think he’s come to give them a scolding, but something is off about the way he’s acting!