Izumi Masamune (voiced by Yoshitsugu Matsuoka) is a writer who focuses on writing light novels. He has won the Rookie Award and embarked on the road of writing. Not long ago, Masamune began living with his unrelated sister Izumi Sagiri (voiced by Akane Fujita). Although they lived under the same roof, Masamune hardly saw Sagiri at home because Sagiri was a super otaku who only stayed in her room and would never come out. The illustrator responsible for illustrating Masamune's novels was an illustrator named "Erotic Manga Teacher". His superb painting skills deeply impressed Masamune. However, the erotic manga teacher had never shown his true self to others. Masamune had many speculations about his true face hidden behind the Internet. However, what Masamune did not expect was that the true identity of this illustrator turned out to be his sister Sagiri!