- "I don't want somebody like that for a Daddy!"
- — Hideyo —
Hideyo appears as a small blue haired boy dressed in brown robes. When acting as part of Tabby's Medic Team, he adds a cat-eared hat with a yellow visor to his outfit.
Hideyo's personality matches his appearance. He generally acts like a small child, affectionately calling other players "big brother" or "big sister". However, his stubborn, childlike personality sometimes causes headaches for his friends. He is unwilling to do anything he doesn't want to do, and nothing can convince him otherwise. He is close to his friend Seisaku, as well as Tabby and Tohta who he calls "Mother" and "Father" respectively.
In the real world Hideyo's player is a twelve-year-old boy named Seiichi Yokoi. He is a friend of Ryouta Noguchi, the player behind Seisaku, who invited him to play the game.
After being contacted by Seisaku, Hideyo joined Tabby's guild, the Paw Pad Squadron, healing people who had been PKKed by Haseo as they traveled The World R:2. After being PKed in the midst of a battle between Haseo and numerous PKers, he decided that helping Haseo was useless and left Tabby's guild, dragging Seisaku with him. Together they decided to create their own healing guild, one that would surpass the one they had just left. With this goal, they formed Medic Union.