Kazuma Akikawa is a character from the 2019 Japanese horror film Sadako, serving as a key catalyst for the film's events. He is the younger brother of Mayu Akikawa, a psychologist working at a Tokyo hospital. Portrayed as a young man who has dropped out of school, Kazuma is an aspiring internet celebrity who produces online videos in the hope of gaining fame and a large viewership. His ambition for recognition drives him to seek out increasingly extreme content for his channel, which he sees as his primary path to success after experiencing early viral popularity.

Kazuma's personality is characterized by a reckless and somewhat misguided determination. When his viewership numbers begin to drop, he decides to become an urban explorer of haunted locations, believing that broadcasting a dangerous stunt will boost his ratings. This decision leads him to investigate a recently burned apartment building, the former home of a mysterious young patient at his sister's hospital. Unbeknownst to him, the site is tied to the supernatural curse of Sadako. His ill-fated excursion into the ruins is streamed online, and he subsequently vanishes, becoming a direct victim of the curse.

In the story, Kazuma's role is primarily that of a plot motivator. His disappearance is the central incident that propels his sister, Mayu, into action. While the film follows Mayu's investigation and her attempts to protect her young patient, it is the search for her missing brother that gives the narrative its driving force. His actions demonstrate how the iconic curse has evolved for the modern era, now spreading through online streaming and viral media rather than just a cursed videotape. His fate creates a personal stake for Mayu, who, as an orphan, considers Kazuma her only remaining family.

Kazuma's relationship with his sister is a key element of his character. Mayu is a dedicated professional, while Kazuma represents a contrasting, less stable path in life. However, her deep concern for him after his disappearance shows the strength of their familial bond. While the narrative does not provide him with a significant arc of personal growth, his character serves as a cautionary figure. His desire for online fame leads him directly into supernatural danger, and his status as a missing person hangs over the entire film. Regarding notable abilities, Kazuma possesses no supernatural powers. His most defining skill is his resourcefulness in creating online content, even if it is ethically questionable, and he is depicted as being active in the digital world of live streaming and video production.