The main character, Harudai Kinugawa, is staying with his aunt and her husband for a while in order to attend a preparatory school.

Just as he is getting used to living in the house, his uncle decides to move out on his own, leaving him alone with his favorite aunt, Shion. Every day he becomes more and more horny living with his overprotective aunt, who unconsciously exudes sex appeal. Furthermore, he even moves in with Reina, his sister who he was close to as a child...

My favorite aunt who I loved like a sister and her friend... The two married "sisters" pamper you, sometimes a little too much, sometimes a little too sexually and the lovey-dovey live-in sex life begins!