A young apprentice detective who helped his grandfather run a detective business. The bulk of their cases were small jobs that mainly involved investigating cheating couples. However, there was one occasion where Shuichi actually solved a murder before the police did.

For this, he was recognized as the Ultimate Detective. But Shuichi believes the case was solved by coincidence and luck, and that he does not deserve the honor of an Ultimate title.

Shuichi's insecurities tend to make him rather timid, but he is quick to act in situations where his keen intuition is needed.