Mai Tadakusa is a high school student from Gifu Prefecture attending the same Nagoya school as Monaka Yatogame. She feels a reluctant affection for her hometown while showing passionate dedication to her personal interests, especially anime. Physically, she stands taller than her peers and possesses a noticeably large chest. Academically, she excels in modern literature but struggles in physical education.

She serves as a cultural counterpart within the group, highlighting regional differences alongside characters from other prefectures. Her interactions contribute to discussions about varying regional norms and perceptions of common sense across Japan.

Mai actively participates in the photography club, where she recruits Jin Kaito. Her family consists of her mother, Mione Tadakusa, and an unnamed brother.

Throughout all seasons, she maintains a consistent presence, functioning as a narrative foil to Monaka's strong Nagoya pride and Jin's Tokyo background. Her character remains stable, consistently embodying Gifu cultural perspectives and participating in group activities showcasing regional dialects and traditions.