When the protagonist finds out his lifelong crush Erika Tachibana divorced her husband and moved into a new house with her 8yr old daughter, he sees the opportunity to move in nearby and babysit Yui.

Since his former crush is no longer a virgin, the protagonist soon sets his sights on Yui, who looks just like her mother. Can he keep it together and earn Yui's trust and respect, or will he lose himself to temptation?