Akihiko Kaji is a tall, athletic man standing 184 cm, with green eyes and short spiky blond hair. His multiple facial piercings contrast with an underlying sensitivity. Born October 21, he experienced a fragmented upbringing marked by financial instability, with his musician father living in Europe and his mother living separately, leading him to rely on discarded convenience store food. He trained in karate and violin from a young age, later majoring in violin performance at Keio University after achieving national-level competition rankings in high school. Outwardly confident and laid-back, he struggles with emotional repression and self-destructive tendencies, often resorting to chain-smoking or transactional relationships. A multi-instrumentalist proficient in violin, drums, guitar, and bass, his musical tastes span classical, metal, ambient, and experimental genres. He initially turned to drumming as an escape from turmoil, later returning to competitive violin. His character arc involves growth through relationships, particularly a toxic co-dependent dynamic with former lover Ugetsu Murata and a subsequent healthier relationship with bandmate Haruki Nakayama, which marks a shift toward mutual support and emotional openness. Over time, he evolves into a more protective partner and mentor to younger band members, reflecting increased emotional availability.