Kakyo Kuzuki is a Dreamseer, known as a yumemi, and a member of the Dragons of Earth, the seven individuals destined to destroy humanity in order to save the planet. He is a young man of an indeterminate age with long, pale hair and distinctive golden eyes. His physical presence is characterized by frailty; he is confined to a bed in a hotel room, surrounded by medical machinery, and is unable to walk or speak in the waking world.

Kakyo's past is defined by imprisonment. His ability to see the future in his dreams was discovered at an early age, leading his own mother to confine him to a small room and use his powers for others, such as helping the mafia. This existence of isolation led to a deep-seated melancholy and a passive nature. He rarely intervenes directly in events, largely believing that any action is futile. His defining personal tragedy is his love for Hokuto Sumeragi, whom he met within a dream. Hokuto brought him to a dream-version of the sea, showing him a freedom he had never known. However, Kakyo foresaw her death at the hands of Seishiro Sakurazuka. Desperate to change her fate, he attempted to escape his prison for the first time but was shot by his captors. He failed to save Hokuto, and the trauma and injury from this event left him in his perpetual comatose state.

As a result of this loss, Kakyo's primary motivation becomes a wish for his own death, believing it is the only way to finally be reunited with Hokuto. He joins the Dragons of Earth after their leader, Fuuma Monou, promises to grant this wish when the final battle concludes. Within the narrative, Kakyo acts as a passive observer who nonetheless holds crucial knowledge. His role is to use his dreams to gather information on the opposing Dragons of Heaven and report to Fuuma. Despite this allegiance, he maintains key relationships that reveal his hidden empathy. He befriends Kotori Monou, another Dreamseer, within the dreamscape. Though he foresees her death, he is moved by her final wish to protect the hero Kamui Shirou and uses his power to briefly possess her corpse to shield Kamui from a fatal blow. He also forms a complex bond with Fuuma, who acts as both his keeper and a source of grim consolation, visiting him in his dreams and offering comfort for his grief.

Kakyo possesses powerful psychic abilities related to dreams. As a Dreamseer, his clairvoyance is said to rival or even exceed that of the celestial Dreamseer, Princess Hinoto. He can see the future, view other people's dreams, and draw both sleeping and waking individuals into his own dreamscapes to communicate or show them visions. He can also project his consciousness to observe events happening anywhere in the world. A rarer ability demonstrated is the power to control a corpse, which he uses to fulfill Kotori's dying wish. Over the course of the story, his deeply held belief that the future is absolute and unchangeable is challenged by Kotori's dying message that the future is not yet decided, offering him a small measure of hope before his eventual end.