Yōsuke Nakamori is the grandfather of protagonist Mai Kazuki and co-leader of the magic troupe Magic Carat with his wife Haruko Nakamori. He actively performs as an illusionist in the troupe’s shows, specializing in acts like making people disappear. Though officially the troupe’s organizer, operational decisions rest primarily with Haruko due to her greater management authority.

Approximately 60 years old, he has grey hair and black eyes. His hobby involves constructing intricate mechanical models—a process demanding such intense concentration that he often becomes oblivious to his surroundings. This deep focus occasionally results in practical oversights in daily responsibilities.

Within Magic Carat, Yōsuke and Haruko serve as paternal figures, guiding and supporting younger members Yukiko Hirota, Susumu Siozawa, and Akira Matsuo. His patient and encouraging demeanor fosters the troupe’s familial atmosphere. Professionally, his extensive stage experience establishes him as a respected veteran magician, though his performances rely on conventional illusion techniques rather than supernatural abilities.

His established traits and role remain consistent in the "Semishigure" OVA and all franchise media.