Ritsuko Mukae enters the narrative as a first-year student at Higashi High School, her life deeply rooted in her father Tsutomu’s vibrant record shop—a hub for jazz sessions where classmates Kaoru Nishimi and Sentarou Kawabuchi frequently gather. A lifelong bond ties her to Sentarou, strengthened by their shared Catholic faith and routine church visits, which later inspire his path to priesthood.

Her shoulder-length dark brown hair, tied in low pigtails with yellow ribbons, frames sharp bangs, brown eyes, and freckled cheeks. The symbolic shedding of her pigtails by the story’s end mirrors her inner transformation. Known for her warmth, optimism, and reliability, she anchors her friends through turbulent moments.

Romantic undercurrents shape her arc: childhood affection for Sentarou gradually shifts toward Kaoru, evolving into a marriage where she takes the name Nishimi and anticipates motherhood. Jazz weaves through these relationships, bridging emotional gaps and sparking collaborations. The record shop’s practice space, orchestrated by Ritsuko, becomes the crucible for Kaoru and Sentarou’s friendship and musical synergy.

A hidden layer of her past emerges in later manga chapters, revealing her skill as a pianist during a poignant duet with Sentarou’s brother on drums. Her journey navigates unrequited love, mended rifts, and the weight of adulthood, all set against 1960s Japan’s shifting cultural tides. Through quiet resilience, she embodies the delicate dance of growing up—where personal dreams, loyalties, and young love intertwine.