Hitomi is a former member of the Code:Breakers, having once held the prestigious position of Code:01, which designated him as the strongest within the organization. He is a tall, slender man with long black hair and distinctive black-blue eyes. The most prominent feature of his appearance is an inverted cross tattoo located on his neck. His demeanor is exceptionally calm and he lives entirely at his own pace, free from the constraints of time. This is reflected in his habits, as he dislikes wearing a watch or carrying a mobile phone, and his favorite pastime is sleeping, often for twelve hours or more a day, particularly enjoying naps in grassy fields. Despite a tendency to be indirect and avoid giving straight answers, he is also noted for his intelligence, gentleness, and a deep, genuine care for both humanity and his fellow Code:Breakers.

Underneath his serene and somewhat lazy exterior, Hitomi is driven by a profound and painful motivation. His time as a Code:Breaker exposed him to the tragic reality of the organization: that its young members risk their lives to fight evil, often dying alone and unknown, with their sacrifices never acknowledged by the world. The repeated loss of these comrades, whom he regarded as his treasures, eventually led him to despise this system. As a result, he betrayed Eden, the organization he once served, with the goal of forcing the public to recognize the existence of the Code:Breakers and their sacrifices. He sought to achieve this by kidnapping a high-ranking official, Prime Minister Fujiwara, in a desperate plan to bring the hidden conflict to light. His actions place him in the role of a primary antagonist, directly opposing the current generation of Code:Breakers who are sent to stop him.

His relationships within the story are deeply influential, particularly his bond with Rei Ogami. Hitomi served as a mentor and close friend to Ogami, acting as both a teacher and an older brother figure. However, their paths diverged due to their different philosophies on justice and the nature of their duty, setting them on a tragic collision course. Hitomi also shares a connection with the heroine, Sakura Sakurakouji, as he seems to possess hidden knowledge about her mysterious past and unique powers. Furthermore, he once showed kindness to a young Miyuki Kanda, saving her and giving her a bird-crested bracelet as a token of his protection. As the story progresses and his body nears its limit, Hitomi ultimately succumbs to Code:End, the inevitable and fatal consequence of a power user overusing their abilities, making him the first in the series to die from this condition.

Hitomi possesses the ability to manipulate electricity, a power that made him an exceptionally formidable fighter. He can generate and control electric currents for a wide variety of purposes, from creating barriers and projecting blinding flashes of light to generating intense, steel-melting heat. The most versatile and dangerous application of his power is the precise manipulation of electrical signals within the brain. This allows him to control the minds and actions of living people, implant memories, and even reanimate corpses by stimulating their nervous systems, turning them into obedient puppets. In addition to his supernatural abilities, Hitomi is a highly skilled tactician and a master of hand-to-hand combat. He possesses considerable physical strength and endurance, able to hold his own against multiple opponents even while on the verge of his own death from Code:End.