Koji Yatake stands 180 cm tall with a broad-shouldered build, sharp facial features, a strong jawline, and narrow eyes typically accentuated by black rectangular glasses, contributing to a serious, intellectual look. His hair is neatly styled and slicked back, reinforcing a composed demeanor. He favors a practical, casual clothing style of loose solid-colored T-shirts with chest pockets, paired with jeans or shorts seasonally, avoiding bold patterns or flashy accessories for a clean, laid-back aesthetic. Born May 10th, a Taurus with blood type A, he took an extra year before entering university. There, he majored in film alongside classmates and close friends Haruki Nakayama and Akihiko Kaji, forming a strong bond with Haruki through collaborative projects. Post-graduation, he works as a video editor at a small company while simultaneously pursuing music as a bassist and vocalist in his own band. He leverages his professional skills to create promotional materials like music videos and photoshoots for bands he supports, often providing these services free to friends. Koji exhibits a calm, mature, and grounded personality, serving as a reliable logistical supporter and emotional stabilizer. He demonstrates high reliability through acts of service, such as organizing the event that became Given's first live performance and stepping in to cover for them during a crisis. His proactive assistance includes creating high-quality promotional content for Given, like editing multi-angle live videos and conducting professional studio photoshoots, significantly boosting the band's early visibility and competition success. Despite his reserved nature, he expresses care through practical support—offering tea, giving haircuts, or bringing gifts like green peppers from the countryside. His interpersonal dynamics reveal protective instincts, particularly toward Haruki. He disapproves of Akihiko Kaji's past behavior toward Haruki, citing concerns about emotional exploitation and financial impropriety, though his disapproval remains a personal boundary rather than active interference, trusting Haruki's autonomy. This reflects a secure attachment style where he regulates his emotions, respects privacy, and offers support without overstepping. His perceptiveness allows him to recognize underlying issues in relationships, like Akihiko's transactional dynamics with others. He meets Yayoi Uenoyama during a live contest and later enters a relationship with her. His dedication to integrating film and music underscores his professional and creative identity. He often worries about Haruki's tendency to overextend himself while maintaining his own band activities and editorial work.