Mafuyu Satou carries a Gibson ES-330 guitar with rusted strings, a relic from his childhood friend and former boyfriend, Yuki Yoshida, who died by suicide before the story begins. This loss left Mafuyu emotionally withdrawn, suppressing his feelings and suffering recurring nightmares. He struggles with self-expression and social interactions, often retreating into silence or fleeing overwhelming situations. Despite his reserved exterior, he possesses sharp perceptiveness, accurately discerning others' unspoken emotions like Haruki Nakayama's feelings for Akihiko Kaji or Shizusumi Yagi's affection for Hiiragi Kashima. An abusive father who physically punished him for speaking contributed to his later reluctance with words. He fears causing unintended harm through careless speech, stemming from a harsh argument with Yuki preceding Yuki's death. When he does speak, his quiet demeanor gives way to unexpected bluntness, directly confronting uncomfortable truths. He occasionally exhibits playful or flirtatious behavior with Ritsuka Uenoyama, demonstrating awareness of his effect on others. After encountering Ritsuka Uenoyama, who repairs his guitar strings, Mafuyu requests guitar lessons. He later reveals a natural singing talent, leading Ritsuka to invite him to join the band "The Seasons," later renamed "Given." Mafuyu initially struggles with lyrics due to unresolved grief. During the band's first live performance, he improvises a raw, emotional song expressing his anguish over Yuki's death, achieving catharsis and beginning to process his pain. He and Ritsuka subsequently enter a romantic relationship. Mafuyu diligently commits to the band, taking a part-time job at a live venue to contribute financially. He forms bonds with bandmates, sharing his past with Haruki and seeking advice from Akihiko. His trauma resurfaces upon encountering Yuki's former bandmates, Hiiragi and Shizusumi, causing him to flee initially. Later, he acknowledges his lingering connection to Yuki while gradually opening up to Ritsuka about their relationship. He continues navigating grief, sometimes fearing history may repeat when Ritsuka interacts with Hiiragi's musical projects. Outside music, Mafuyu cares for a Pomeranian dog named Kedama, a gift from his mother to alleviate loneliness. He participates in school activities like basketball with classmates Shogo Itaya and Ryu Ueki. His journey involves learning to articulate his emotions, as shown when he confesses to Ritsuka on school stairs about having "truly loved someone," signifying ongoing growth. Akihiko later warns him that unresolved past issues may hinder his lyric-writing, highlighting his continued emotional challenges.