Ichika doesn't like to be in front of people, but when she cosplays, she becomes cheerful and energetic as if she is a completely different person. She poses cutely in front of her brother and the photoshoot begins, but the brother also has a strange sexual fetish and masturbates every day while fantasizing about his sister's still developing body. On this day, he has a private photoshoot with his sister, but the brother skillfully drags his sister into the world of eroticism and commits incest.