Boku no Pico

All character design was done by Saigado.

Pico

Pico (ぴこ, Piko)

Voiced by: Mariko Sakou

A blonde-haired boy who works a part time job at his grandfather's bar in the summer. He's often shown swimming, usually naked or in a blue Speedo. He has worn girls' clothes ever since Tamotsu (Mokkun) gave some to him as a gift. Later, feeling hurt that Tamotsu wouldn't define their relationship, he rebels by cutting his hair and running away from home, although later on they reconcile. The following summer, Pico meets Chico, who is swimming naked in a stream, while riding his bike. He soon becomes friends with Chico, who calls him "Oniichan" (big brother), and they form a romantic and sexual relationship. In his relationships with both Mokkun and Chico, he is the uke, though in the latter relationship this is somewhat reversible.

Tamotsu

Tamotsu (タモツ), also known as Mokkun, is a white-collar worker and regular at Bebe.[3] He seduces Pico after mistaking him for a young girl, but continues the relationship after discovering Pico is in fact male. He later buys Pico a girl's outfit, complete with a ruby choker and panties, which he persuades Pico to wear despite his initial protests. He views Pico solely as a sexual object, though later shows true concern for Pico after he disappears. Although he eventually reconciles with Pico, he is absent in the second and third OVAs. In his relationship with Pico, he is the seme.

Ojiisan

Ojiisan (おじいさん) is Pico's grandfather who runs a large but usually empty bar by the beach named Bebe. When Tamotsu visits him for the summer, he has Pico help out as waiter, which involves wearing a frilly pink apron. He introduces Pico to Tamotsu and suggests they spend time together.

Chico

Chico (ちこ, Chiko)

Voiced by: Aiko Ōkubo

A brunette boy who lives with his older sister in a large house in a secluded forest area and develops a sexual relationship with Pico in the second episode. He is younger and less sexually experienced than Pico. He often plays in the outdoors nude and secretly watches Oneesan masturbate. In most cases, Chico is the seme, despite his age, though his relationship with Pico is somewhat reversible.

Oneesan

Oneesan (お姉さん) is Chico's older sister and legal guardian. Perhaps because of her caring for Chico, and her isolated home in the countryside, she appears sexually frustrated and masturbates regularly. After being caught masturbating by the boys through a crack in her bedroom ceiling, she becomes the indirect cause of their experimentation. She has a large collection of cosplay outfits and sex toys that Pico and Chico use without her permission. She later fondles herself away from the boys when she finds them sexually engaged upon returning home from the grocery store.

CoCo

Coco (ここ, Koko) is a feminine-looking boy with long, black hair who Pico and Chico meet in the third episode. It is subtly implied that Coco is actually a so-called "city fairy", due to some strange minor occurrences in his vicinity, though this is never explicitly confirmed. Coco soon has sexual relationships with both Pico and Chico. After inadvertently causing some friction in their relationship, Coco decides to distance himself from Pico and Chico, though they do reunite with him at Tokyo Tower and end up having a threesome. He is also the main uke of the three, but this can be reversed.

• Official Site (in Japanese)
• Boku no Pico (anime) at Anime News Network's encyclopedia