Pico

Pico is 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 Tamotsu suggests it. Later, hurt that Tamotsu wouldn't define their relationship, Pico rebels by cutting off most of his hair and running away.

The following summer, Pico 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. In his relationships with both Tamotsu and Chico, he is the uke, though the latter is somewhat reversible.

(Source: Wikipedia)