Chiriko Tsurumi, called Tsuruko, belongs to the Super Peace Busters, childhood friends scarred by Meiko "Menma" Honma's death. She possesses dark blue hair, green eyes, and usually wears glasses. Attending an elite high school with fellow member Atsumu "Yukiatsu" Matsuyuki, she ranks fourth in her class but strains to maintain this position against Yukiatsu's academic performance. Tsuruko presents a serious, logical, and observant nature, frequently voicing critiques within the group. She openly chastises Naruko "Anaru" Anjou for her follower tendencies and expresses doubt regarding Menma's spectral return, questioning Menma's forgiveness. Despite her reserved exterior, Tsuruko harbors deep-seated feelings for Yukiatsu, believing he cannot reciprocate due to his fixation on Menma. She privately keeps and occasionally wears a hairpin Yukiatsu discarded after Menma rejected him, a token of her unrequited affection. Her relationship with Yukiatsu is intricate; they remain close and are often mistaken for a couple. Tsuruko acts as his voice of reason and guardian, aware of his guilt over Menma's death and his coping mechanisms, including wearing Menma's dress. She sketches, sometimes depicting Yukiatsu in Menma's dress, reflecting her inner conflict. In a vulnerable confession to Anaru, she states, "Yukiatsu will never choose me... even if Menma goes to Heaven, you're the one who's his backup," revealing her resignation. Initially reluctant during the group's efforts to help Menma move on, Tsuruko grows more invested in resolving their shared guilt. Her typically composed facade cracks during emotional moments, such as crying when Yukiatsu hurts her hand. A decade after Menma's passing, Tsuruko works as a web designer. Her relationship with Yukiatsu stays ambiguous; they never married, citing the "right timing" not arising, yet maintain a connection. At a reunion in their childhood hideout, she witnesses Jinta "Jintan" Yadomi propose to Anaru. Tsuruko continues engaging with the group, reflecting on their carved promise to remain friends and accepting that while circumstances shift, their bonds endure.