Yūichi Aizawa appears as a supporting character within the *Orpheus Order* storyline of *Phi-Brain: Puzzle of God*. He attends Root Academy as a student and belongs to the school's Puzzle Club. Physically, Aizawa is chubby, with short black hair and black eyes, and wears the standard male uniform of Root Academy. He is friends with fellow student Naoki Takeda.

His role centers on his Puzzle Club affiliation, placing him within the group encountering the series' central puzzle-solving challenges. He appears in a supporting capacity relative to the season's main protagonists and antagonists. His background, motivations, personal conflicts, and significant character development remain unexplored within the *Orpheus Order* season, other seasons, movies, OVAs, or spin-offs.