Tonomura Zenji is a poor student from the countryside who moved to Tokyo to attend university. Attracted by the convenience of getting to university and the exceptionally low price, he decided to live in the cheap apartment Momoyamaso, but he was worried that it might have a bad reputation. However, Momoyama Marin, the landlord of Momoyamaso, is a stunning beauty and she has big breasts. His new life is filled with hope and anxiety. While he feels happy with Marin's misleading behavior, he is terrified of being attacked by sleep paralysis every night. Yes, the landlord, Momoyama Marin, is just a disguise. Her true nature is... a succubus named Marin.