Mizuho Tanonaka is an animator at Studio Petit, working under production desk manager Mikiko Oguro. He contributes to multiple anime projects simultaneously as the studio faces overlapping deadlines. His work philosophy is defined by the consistent catchphrase "even the bad stuff," signifying his acceptance of all aspects of animation production, including challenges and imperfections. This phrase remains central to his character in both the original OVA and its sequel.

When the studio brings in a veteran producer to enforce strict deadlines over quality, Mizuho is among the staff impacted by this shift. The resulting tension sparks disagreements within the team between creative standards and scheduling demands. His presence and reactions form part of the studio's broader dynamic during this conflict.

His role focuses entirely on his function within the animation team at Studio Petit, reacting to production pressures and management changes while maintaining his established perspective. His portrayal is confined to the two OVAs, with no significant individual character arc, background story, or personal development detailed. Information about appearances in spin-offs or expanded media is absent.