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?

December 25 is Keiichiro’s birthday, and Yuri’s been hard at work at her part-time jobs in order to throw a lovey-dovey, hot, super-gorgeous birthday party for Keiichiro—until he tells her not to bother, that is! Christmas is supposed to be the time for couples to celebrate together, but it seems there’s only trouble on the horizon!