Сотоїн Манабу

The leader of the Pretty Boy Detective Club. Also known as "Manabu the Aesthete." Mayumi calls him "the leader."

He is so stupid that he claims to be uneducated and acts cheerfully and arrogantly without reading the atmosphere, but always seeks beauty and will not do anything that goes against aesthetics. Although he often does nothing but gives orders, he is recognized as a leader by the group.

It's revealed at the end of the first volume that he's a 5th grade at Yubiwa Academy Elementary School.