Machi Tokiwa is a 14-year-old middle school senior and serves as the student council president at Yuihama Middle School. She is the younger sister of Sari Tokiwa, a teacher at the same school. Machi has neck-length caramel-brown hair, caramel-brown eyes, and wears red-framed glasses. She stands 163 centimeters tall and weighs 50 kilograms, with a birthday on August 5 and blood type B. Her favorite flower is the sunflower.

Machi presents herself as strict, serious, and disciplinistic, holding herself and others to high standards. Despite this outwardly tough demeanor, she has a soft spot for her best friend and classmate, Tami Nishimikado, and finds it difficult to refuse Tami's requests. She also has a weakness for sweet things. Initially, Machi is hostile toward the formation of the yosakoi club, partly because the club's early members, Naru Sekiya and Hana N. Fountainstand, were using the school rooftop without permission, and partly due to a strained relationship with her older sister Sari. Machi had long admired Sari but felt abandoned when Sari left home, causing a rift between them. She objects to Sari becoming the club's advisor.

Through the efforts of Tami and the other girls, Machi begins to understand her sister's true feelings and reconciles with her. This resolution allows Machi to let go of her grudge and join the yosakoi club herself, becoming an active member of the group. Her role in the story evolves from an initial obstacle to a supportive participant, and she grows more open and trusting as she works alongside her friends. While she has no special abilities beyond her duties as student council president, she later learns to dance yosakoi and contributes to the club's performances. Her development is marked by her willingness to overcome personal resentment and embrace a new activity alongside her classmates.