"The Adventures of Ai and Rin: Joining Forces against Evil" is the story of the sorceresses Ai and Rin, fighting an ancient evil represented by monsters with tentacles.

According to legend, the future wife of the heir should be the girl who will have an unusual sign on her neck during orgasm... Now Tony Take has to choose a wife, but the problem is that there are many girls, and only one of them will have a true bride. There is only one way to find out which girl is destined to become his bride.

The main character of this romantic story moves in with his stepsisters in the summer. All of them, without exception, are in love with him. One of them innocently touches his shoulder on the bus, the other, sitting in her room, shows how she can dance, and classmates also begin to show interest in him.