Masayan belongs to Team Tonegawa, the project team Yukio Tonegawa formed within the Teiai Group. He is one of the original blacksuits tasked with creating the "game of death" designed to relieve Chairman Hyōdō's boredom.

Kenji Yamazaki, a prominent blacksuit leader and key subordinate of Tonegawa, holds explicit responsibility for Masayan's care and supervision as part of his team duties.

Masayan never speaks. He remains completely silent across all depicted interactions and meetings, contributing no verbal dialogue. His presence is defined by this silence, primarily observed in group settings alongside other team members.

His role serves as a narrative device emphasizing the dehumanizing nature of corporate structures. Masayan personifies the anonymity and pressure experienced by mid-level employees within rigid organizational hierarchies. The demanding deadlines, unpredictable leadership, and internal conflicts faced by Team Tonegawa form the backdrop for his silent, faceless presence. His characterization focuses entirely on this non-verbal role within the team and his reliance on Yamazaki's guidance.