When my parents were away on a trip and I was home alone, my sister came home with her girlfriends who were rumored to be super sluts! While he was upset, his sister told him, "You can do whatever you want with her friends!" The protagonist, who was excited to see his sister's slutty friends making dirty jokes one after another, mistakenly thought that he could have sex with anyone, and his delusions and groin swelled. In this unbelievable heavenly situation, the protagonist's rampage knows no bounds, and he immediately inserts himself into his sister's slutty friends one after the other! A harem fantasy of "I wish something like this could happen" with a series of unexpected lucky lewd encounters!