Kōzō Ryūga is a human character from the 2023 anime film The Birth of Kitaro: The Mystery of GeGeGe. He is the second son of the Ryuga family, a wealthy and superstitious clan that controls a remote village and is the source of a mysterious drug called M. Some time before the events of the film, Kōzō violated a strict family taboo by setting foot on a forbidden island near the village. This transgression caused him severe mental distress, leaving him psychologically broken. As a result, he appears considerably older than his actual age, with wrinkles and white hair. Since then, he has lived in isolation in a storehouse, spending his days absorbed in drawing pictures.

His personality is that of a withdrawn and traumatized individual, largely detached from the machinations of his family. He does not play an active role in the family’s schemes; instead, his presence serves as a haunting reminder of the darkness surrounding the Ryuga household. Kōzō does not possess any supernatural abilities. His only notable trait is his compulsive drawing, which may be a form of coping or a way to convey hidden knowledge. He has minimal interaction with other characters, though his broken state and the circumstances of his downfall provide important context for the mysteries tied to the village and his family.

Kōzō is not portrayed as antagonistic; rather, he is depicted as a tragic figure shaped by the family’s long‑held secrets and the supernatural forces at work in the region. His character remains static throughout the film: his backstory is gradually revealed, but he undergoes no personal change. His key relationships are defined by his position as the second son of the Ryuga family, though the exact nature of his bonds with his siblings and father is left ambiguous. Notably, his name lacks the character 時 that appears in the names of the other designated heirs, suggesting he was never intended to inherit the family legacy.