During your summer vacation you stay at your aunt's house for a week. Living there are two cute young girls, 10 year old Arisu and 7 year old Karin your younger cousins. A chance meeting with a classmate of Arisu, a boy who goes by the odd name of Gorizou finds you in possession of some of his collection of pornography; it's every young man's dream!

However Arisu finds the magazine you borrowed and shares it with Karin. Now the two believe it's only natural that two people in love have sex together and since they both love you they decide to start on an ecchi journey with you!