Kazuki Amamiya is a Japanese novelist and scenario writer known primarily for originating the light novel series Haibara's Teenage New Game+. Amamiya won the grand prize at the HJ Novel Award in 2020, which led to the series' publication.

Haibara's Teenage New Game+ is Amamiya's most notable original work. The light novel series, illustrated by Gin, began publication under Hobby Japan's HJ Bunko imprint on December 1, 2021, and had released nine volumes as of July 2025. The series is licensed for English release by J-Novel Club. The story follows socially anxious college senior Natsuki Haibara, who finds himself transported seven years into the past to one month before his first year of high school, giving him a second chance to reshape his teenage years. The work has also been adapted into two manga versions. A full-color vertical manga illustrated by Misaomaru was serialized on Hobby Japan's Comic Fire website from June 2023 to August 2024, followed by a sequel manga illustrated by Comochiya beginning in December 2024. A television anime adaptation of Haibara's Teenage New Game+ is scheduled to premiere in April 2026, produced by animation studio Studio Comet.

Beyond Haibara's Teenage New Game+, Amamiya has authored other light novel series, including Hero and Witch's Reincarnation Love Comedy and Witches Select: The Heroic Legend of Two Witches. Information regarding Amamiya's personal background, artistic identity, recurring thematic interests, and broader industry significance is not available from the provided search results.