"Bloody Demon" is what this criminal was nicknamed at the police station; the police tended to give names to especially flamboyant crimes. According to Ayatsuji, this is stupid.

"Blood Demon" is a rather smart and dexterous criminal, which Ayatsuji could not find for a long time, at least a single a clue for the investigation. But one time, on purpose or by accident, the “bloody demon” nevertheless made a mistake - and here they are.

Ayatsuji stood in an abandoned building. Not a single clue could have led him here, except for an anonymous letter of invitation, which somehow ended up on his desk just when Ayatsuji latched on to a detail of the investigation that could indicate the identity of the culprit, or at least narrow the circle investigations.

In a letter, an anonymous user said that he could help in the investigation. Ayatsuji would not have paid attention to these words, much less would have come here, if only the contents of the letter were not “interesting.”

It took some effort for Ayatsuji to escape from surveillance again.