In Episode 19, the team explores an old love hotel built on a dragon vein, a place known for its intense spiritual energy. The hotel, once owned by a criminal organization, is haunted by the ghosts of women who were abused and killed there. These ghosts are trapped and tirelessly search for a way out, but disappear before they can find it. This phenomenon creates a "secret space" that does not physically exist.

Yayoi has hidden a powerful spirit, the "Graduate," in the bathroom of this secret space. However, the spirit, a courtesan, has manipulated the space so that only those she chooses can enter, and she particularly dislikes Yayoi. Keitaro is tasked with entering the secret space, as the courtesan spirit only grants access to men.

Keitaro follows Yayoi's instructions to navigate the shifting realities of the hotel and finally reaches the secret space. There, he encounters the courtesan spirit, who tries to deceive him by taking the form of his teammate Eiko. The spirit attempts to manipulate Keitaro into releasing her, but he sees through the deception and resists.

Meanwhile, Yayoi and Eiko search for Keitaro. Eventually, they find him battling the courtesan spirit. Keitaro uses a special item to reinforce the spirit's seal, which helps him escape her control and return to reality.

The episode also touches on the concept of ghosts and humans swapping places, a phenomenon Keitaro briefly experiences during his encounter with the courtesan spirit. This revelation sparks a discussion about the possibility of evil spirits walking among humans, disguised as people.

The episode ends with the team preparing to investigate the Old I Watergate, a haunted location with an S-rank. Unbeknownst to them, strangers are also searching for a stolen relic, leading both parties to the same destination. The episode concludes with the introduction of a mysterious, abandoned boy who casts a shadow into the twilight, setting the stage for the events of the next episode.