Yuuichi Katagiri is a hardworking lad who believes friends are more important than money. In reality, he is a really dead broke student and has multiple part-time jobs to barely live for. He is secretly "the mind" of the team that has managed himself in making all the odds come right to his favor with all might. He also had a rather very heavy past that makes him considered a "devil" and "dangerous."

Spoiler

In Chapter 99, it is revealed that Katagiri Yuuichi is the one who created the prototype for the "Tomodachi Game".