Genmukan

Satori Kido is a humble detective who doesn't have much of a job or finances. He lives in a converted emergency house that serves as his office. Despite this, there are a few nice things in his life, such as a woman who is his secretary, assistant and informant, performing all these duties for a token payment.

One day, during his usual work (moving papers from one place to another), Kido discovered a strange letter. It made him suspicious and he decided to get rid of it, but his secretary opened the letter. Inside the letter was an offer to investigate. At first, Kido was reluctant to take on this assignment, but after some deliberation, he agreed, attracted by the prospect of a monetary reward.

After carefully studying the letter, he realized that he needed to find a stolen stone that had gone missing from a mansion where several people lived. The next morning he was taken by boat to this mansion, which was built on a remote island. As he crossed the threshold of the house, the detective sensed that it might be a trap.