Nagato Shinobu is a simple student who all of a sudden finds himself in deep when the most popular girl in class, his childhood friend, and an old unrequited love all confess to him at the same time! His eroge-filled youth is about to begin!

Murakami Teruaki's new project is finally starting! This new production of Murakami Teruaki, greatly known for his savage eroticism unrivaled in depictions of high-speed piston-like action and facial expressions accompanying orgasm, is, of all things, in the genre of "Younger Sister Moe"! It has been decided that Murakami Teruaki will turn Moonstone Cherry's "Imouto Paradise!", a game with the concept of "masturbate to cute girls," into an anime with the help of his direction!! The lewd, cute younger sisters will now assertively bear down on you through the anime.

Based on the game by Guilty. Yunoki Mio excels in both academics and sports. She is the student council president at a rigorous academic institution. She passes the busy yet fun-filled days with her childhood friend Ayukawa Rinka, cousin, Ikoma Yui, and fellow student council member who idolizes her, Asahina Konomi. Mio's parents mostly work overseas and are thus often away from home, but she does not feel lonely thanks to the family's live-in helper, Toya Shiori. They share a sisterly love for one another and treat each other as family. Mio leads a thoroughly fulfilling life. But one day, she is befallen by unexpected misfortune...