Second-years Mao Tsuchiya and Hisashi Otomo make three promises: 1) That Mao will never tell anyone that Hisashi is gay and has a boyfriend, 2) That Hisashi will never think of Mao in that way, and 3) That they'll always knock before entering, in case someone is having some private time. The two's ground rules should ensure a peaceful life together in their dorm, but life is never as simple as it should be, and some things are not so easily promised...