Akihito Kanbara is a half-human, half-youmu hybrid with immortality and rapid regenerative healing that recovers nearly any injury. His human mother is Yayoi Kanbara, and his father is a powerful unidentified youmu. A childhood car accident exposed his regenerative powers, leading to social isolation. Later, an incident where his youmu side nearly killed Hiroomi Nase prompted the Nase family to monitor him. He displays a playful, friendly demeanor laced with sarcasm and a defining obsession with glasses, calling himself a meganest. This fixation first attracts him to Mirai Kuriyama when he stops her from jumping off their school roof. Despite her repeatedly attacking him with her blood sword, he empathizes with her outcast status due to her cursed blood abilities, and they form a deep bond. His youmu half, called Beyond the Boundary, emerges as a feral, destructive entity during life-threatening injuries, marked by physical changes such as black eyes with multicolored irises and green-highlighted blonde hair. During a phenomenon known as the Calm, a rampage endangers others, and Mirai defeats the transformed Akihito by absorbing Beyond the Boundary into herself, leaving him in a three-month coma. Awakening, he discovers Beyond the Boundary still battling Mirai in a pocket dimension. He enters this space and helps her defeat the entity, after which she sacrifices herself and disappears. Mirai later returns alive but with amnesia. Akihito chooses to conceal their past to protect her chance at a normal life, but when she is consumed by darkness, he confronts her, reaffirms his love, and accepts her without glasses, cementing their romance. His abilities include immense strength, earth manipulation, pyrokinesis, electrical attacks, and resistance to spirit warrior seals. He is a second-year high school student and member of the Literary Club. His relationships include a teasing friendship with Hiroomi and Mitsuki Nase, who monitor him, and his eccentric mother Yayoi.