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?

After Yuri begins dating Keiichiro, she discovers what it's like spending time with a member of the elite. When they commute to high school, they're chaperoned by Keiichiro's private guards, and there are surveillance cameras in his chauffeured car. It's difficult to be romantic, especially now that a handsome spy from the Katsuragi family is interfering in their relationship!