Every time a widespread supernatural incident involving youkai occurs in Gensokyo, shrine maiden Reimu Hakurei usually solves the dire situation by confronting the perpetrator. However, cases targeting specific people where culprits hide their identities are usually too delicate for the youkai exterminator to handle.

Enter Satori Komeiji, the mistress of The Palace of Earth Spirits. As a satori youkai, she possesses a third eye that allows her to read minds, detecting any criminal no matter what lies they may try to pull off. With her extraordinary aptitude as a detective, Satori is able to solve all mysteries laid upon her⁠—even if she does not always want to go outside her mansion.