Yuuichi is Punpun's uncle from his mother's side.
History
When Yuichi was 28, he worked as a ceramics class teacher. He was very popular with his students. He had a brief affair with a 16 year old student girl, who was the daughter of Mrs. Yagi, who was also another student of his. He quit his job after Washio, a ceramics co-worker, injures Mrs. Yagi on the request of her daughter.
Appearance
Yuichi always wears a beanie and glasses, although he sometimes takes the glasses off. Yuichi looks just like Punpun. At times, Yuichi appears to have human eyes, and develops facial hair several times.
Personality
Yuichi is somewhat of a pervert, and often stares at girls' butts when he gets the chance. His appetite for women is one of his few apparent flaws, as he has had several affairs which affected his romantic relationships. Yuichi is extremely remorseful about his adultery, to the point of suicidal thoughts.
He does not believe in God and has little patience for people who force their religion onto others, as seen when he snaps at Aiko's mother when she goes door-to-door selling blessed water.
Family
Yuichi acts as a secondary father figure to Punpun, assuming care of him once his father is sent to prison. During this period, Punpun's mother, Midori, Yuichi, and Punpun share a house.
When Punpun finishes highschool, Yuuichi marries Midori Ookuma. Later on he and Midori have a child in the end of the series.