Hiiragi Kashima appears throughout the Given franchise as bassist and later vocalist for the band syh, originally formed in high school with childhood friends Shizusumi Yagi on drums and Yuki Yoshida handling vocals and guitar. After Yuki's suicide, syh persists as a duo supplemented by temporary guitarists until Hiiragi recruits Ritsuka Uenoyama as a temporary replacement. Physically, Hiiragi stands 175 cm tall (approximately 5'9") with a lean, athletic build suited for performance. His sharp yet approachable features include almond-shaped eyes conveying intensity or concern, thin expressive eyebrows, and tousled blonde hair featuring choppy bangs framing his face. His style evolves from youthful, preppy high school attire to more structured, mature clothing in adulthood, reflecting his emotional journey. Personality-wise, Hiiragi combines outward charisma and social adeptness with deep emotional complexity. He projects confidence and energy, easily drawing people in. Beneath this lies unresolved trauma from Yuki's death, manifesting as guilt, regret, insecurity, impulsivity, and defensiveness. He often masks vulnerability through sarcasm or deflection. Loyalty to childhood friends remains a core driver of his actions, even during estrangement. His background involves growing up alongside Mafuyu Sato, Yuki Yoshida, and Shizusumi Yagi. Hiiragi witnessed Yuki and Mafuyu's relationship but never intervened—a decision haunting him with guilt after their falling-out preceded Yuki's suicide. He blamed himself for not supporting Mafuyu, causing a prolonged rift. Years later, an accidental encounter prompts Hiiragi to actively seek reconciliation, questioning if Mafuyu's return to music signifies healing or attachment to Yuki. During a rain-soaked meeting, Hiiragi confesses his desire for forgiveness, particularly from Mafuyu, acknowledging his past inaction. Hiiragi's relationship with Shizusumi evolves significantly. Initially unaware of Shizusumi's longstanding romantic feelings, Hiiragi relies on him emotionally, revealing his脆弱 only in Shizusumi's presence. After a confrontation where Shizusumi mistakes Hiiragi's admiration for Yuki as romantic love, Hiiragi reevaluates his feelings. He recognizes his admiration was platonic—rooted in viewing Yuki and Mafuyu's bond as an idealized first love—and realizes his authentic love for Shizusumi. Their subsequent romantic relationship stabilizes Hiiragi, though their dynamic retains its characteristic banter and mutual support. Regarding Ritsuka Uenoyama, Hiiragi initially resents his presence in Mafuyu's life, perceiving it as a replacement for Yuki, leading to tension. Their collaboration in syh, however, gradually fosters mutual respect. Hiiragi's development culminates in completing Yuki's unfinished song as a tribute, symbolizing acceptance of the past. By the franchise's later stages, including the 10th Mix manga and Hiiragi mix film, he achieves greater emotional maturity, balancing his music career with a committed relationship with Shizusumi. His surname 鹿島 (Kashima, meaning "Deer Island") and given name 柊 (Hiiragi, referring to Japanese holly) reflect cultural symbolism tied to nature and protection, aligning with his role as a protective yet resilient figure.