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?

Keiichiro and Yuri have finally kissed, which means they’ve broken the Katsuragi code! Now they’re being taken to the Katsuragi family’s first residence, where the final boss—Keiichiro’s grandfather—awaits! The family convenes to make Keiichiro pay for his crime, but can anyone stop this couple’s love when Yuri is on a rampage?