Chiriko Tsurumi, nicknamed Tsuruko, stands as a central figure in the childhood friend group Super Peace Busters. Her dark blue hair, green eyes, and slim build are frequently framed by glasses and a school uniform of a dark blue skirt and button-up tank top. Known for her serious, logical demeanor and sharp critiques, she directs particular scrutiny toward Naruko "Anaru" Anjou, disapproving of her tendency to mimic others. Academically driven, she attends an elite high school with Atsumu "Yukiatsu" Matsuyuki, where her fourth-ranked status fuels quiet insecurity in the shadow of his consistent academic dominance.

Beneath her composed exterior lies unrequited feelings for Atsumu, carefully concealed due to his unresolved attachment to the deceased Meiko "Menma" Honma. She secretly treasures a hairpin Atsumu once gifted Menma, occasionally wearing it alone, and sketches him during introspective moments—subtle acts reflecting her suppressed longing. Following Menma’s death, she and Atsumu maintain a closeness often misread as romantic by peers, though their bond remains strained by emotional distance and unvoiced tensions.

When Menma’s ghost reappears, Chiriko initially doubts her motives but joins the group’s mission to help her move on. Her incisive critiques push others to confront hidden guilt and self-deception, even as she wrestles with her own defenses. A symbolic haircut marks her struggle to shed childhood attachments, signaling tentative steps toward emotional growth.

A year later, she channels her emotions into drawing, creating artwork that includes Menma—a quiet acknowledgment of acceptance. Though still withholding her feelings from Atsumu, their interactions hint at fragile understanding. His gift of a hairpin resembling Menma’s underscores a shifting dynamic between them. Her journey weaves intellectual rigor with vulnerability, tracing a path from guarded stoicism to cautious openness, anchored by unresolved yearning and incremental self-discovery.