Starting with a lewd dream about his 5 sisters in compromising positions, our protagonist's life is about to level up! While his parents are away on a trip for a month he is assaulted by his youngest and oldest sister's sexual desires, his dream starts to become a reality...

It's summer vacation and Keiichi's parents left him with his five younger sisters to go on an overseas trip. Now with their parents far out of the picture, his younger sisters are aggressively making their moves on him. Of course there's no way he can hold back.

A guy and his younger sisters have sexual fantasies-which is completely normal for their ages-. But the important fact is that they have naughty sexual fantasies about the sisters or the brother. They ignore this and simply think they are perverted and have sinful desires. Until one day they found out about the others feelings and all hell breaks lose in the house. And the girls decide to please the otaku-like desires of the brother by dressing as his favorite anime and eroge characters.