Kei Sakai, a high school boy, had a problem. One thing led to another, and he was deeply uninterested in everything and had no sexual desire. Then one day, he learns of a mysterious, beautiful girl named Yam...

The main character lives more or less a secluded life working as an ero mangaka... Suddently his younger sister Sora arrives at his home, telling him that their father has left a goodbye note and is nowhere ...