Monaka Yatogame is a 16-year-old first-year student at Tagane High School in Nagoya. Raised primarily by her grandmother, she speaks fluently in a traditional Nagoya dialect, modelled directly after her grandmother's old-school speech patterns, including nuanced local pronunciations like the distinctive intonation of "deshou." Though occasionally self-conscious about her accent, she becomes fiercely protective of it and Nagoya's culture when facing criticism. This strong hometown pride drives her to actively confront newcomers from Tokyo who display ignorance or disrespect toward local customs.

Her physical appearance features distinctive hair styled to resemble cat ears, and she sometimes exhibits cat-like behavior, particularly around classmate Kaito Jin. Her family includes her mother, Ayami Yatogame, and a grandmother shared with her cousin, Shiharu Itemae, who uses the nickname "Mona-nee," much to Monaka's dislike.

Initially part of the photography club with Kaito Jin, Mai Tadakusa, and Yanna Sasatsu, her social circle expands in later seasons to include student council members Shō Kochikashi, Kei Aonaji, and Kiina Asaka. Season 4 features intensified interactions amid faster-paced dialogue, including an episode centered on a crisis involving Nagoya's culinary identity, specifically chicken wings, highlighting her deep cultural ties. Her grandmother's influence remains profoundly evident in shaping her speech and values, while her mother's presence is acknowledged but less prominent.