Karasuma Kotarou

“Ahh, stop arguing already!”

The protagonist’s classmate who’s been given the unwanted nickname “Omaru.” Since it was his fault that Michiru broke the statue, he also joins the Bureau for the Investigation of Special Affairs. He has the most common sense out of the three Bureau members, so he’s always mediating between Michiru and Ushio with phrases like “Now, now” and “Calm down.” He has a strong sense of responsibility, can’t leave distressed people alone, and has a caring, softhearted personality… but his bad luck gets him into all sorts of trouble. His hometown is out in the countryside, so he is unfamiliar with city life and gets surprised at various things.

Spoiler

Kotarou and Mutsuki are revealed to be alternate identities, except for the fact that Omaru was predominant over Mutsuki, whom Omaru was "occupying".