Pico

Who is Pico?

A blonde pre-adolescent boy who works part-time at his grandfather's bar in the summer. He's often shown swimming, usually naked or in a blue speedo. He wears girls' clothing after when Mokkun suggests it. Later, hurt that Tamotsu wouldn't define their relationship, he rebels by cutting off most of his hair and runs away. The following summer, he spots Chico swimming nude in a stream while cycling. He soon befriends the other boy, who calls him "oniichan" and forms a sexual relationship with him.

Biography excerpt via Kitsu.