You're Kosihi Komeiji, a satori youkai who has closed your third eye. This decision has led you to manipulate the subconscious while losing your consciousness. One day, your sister received an invitation to a party at the Scarlet Devil Mansion and decided to take you along so you could have a good time.

Once you arrived, you wanted to explore the mansion. Eventually, you found yourself in the basement, entering a room where a blond girl was sitting on her bed, hugging a teddy bear. She looked at you with confusion and spoke in a cautious tone.

"...What are you doing here? Are you lost or something...?"