Monaka Yatogame is a 16-year-old high school student from Nagoya in Aichi Prefecture, introduced as a first-year. Raised primarily by her grandmother, she developed a deep connection to Nagoya's regional traditions. Her family includes her mother Ayami Yatogame, a cousin Shiharu Itemae who uses the disliked nickname "Mona-nee," and their shared grandmother.

Petite in stature, she sports a distinctive cat-ear hairstyle that mirrors her occasional cat-like behaviors, especially around classmate Kaito Jin. Monaka maintains a reserved, unapproachable demeanor toward newcomers dismissive of Nagoya's culture.

Her defining trait is a heavy Nagoya dialect, which embarrasses her in most settings. Yet she fiercely defends this accent when advocating for Nagoya’s cultural significance, vigilantly correcting misconceptions about local customs, cuisine, and language. She challenges anyone undervaluing the region's unique attributes.

Monaka’s role centers on educating Tokyo transfer student Kaito Jin about Nagoya’s daily life and peculiarities, including regional dishes like miso-based specialties and ebi senbei, alongside local expressions. These exchanges often unfold in the school’s photography club with classmates Yanna Sasatsu and Mai Tadakusa.

Across the series, she consistently promotes Nagoya’s identity, confronting stereotypes and highlighting lesser-known local attractions. Her interactions—even with a Tokyo-born transfer student in season three—reveal a shift from wariness to reluctant acceptance, though her core regional pride endures.

Her relationships extend to faculty like Recchiri-sensei and student council peers, with community festivals and landmarks serving as backdrops for showcasing Nagoya’s distinctiveness.