Keine Kamishirasawa is a school teacher. It’s rumoured that her lessons are difficult and boring. She doesn’t just hold classes for humans, but for fairies and youkai as well.

The hakutaku is a youkai that appears before virtuous monarchs to warn them of future disasters and lead them onto the path of righteousness. Keine is extremely knowledgeable and is the most intelligent of all half-human half-beasts. She is a half-beast with the ability to “eat” history and transforms into a hakutaku upon seeing the full moon.

Keine possesses a different ability in each form. In human form, she is able to “eat” history. While transformed into her beast form, she can create history. All of Gensokyo’s history is created by her.

During the Kosuzu Motoori Case Files incident, the original sourcebook for the Hieda household’s Gensokyo Chronicle, went missing! Keine, who was completely unaware, lent a certain book to Mokou. Keine and Mokou never imagined this would lead to them becoming suspects.

Keine rushed over to the Hieda residence upon hearing that the original sourcebook for the Gensokyo Chronicle had gone missing. Because both the book and Akyuu are so important to her, she dropped everything in her rush to get there. However, the clever detectives were already enjoying a celebratory tea party by the time she arrived.