Youmu in the Nightmaretaker: Akuma ni Tsukareta (lit. "Youmu, Possessed by a Demon") is a purported 2021 Japanese-style horror-action game or music video circulating in niche online forums. The title combines Konami’s obscure 1981 arcade game The Nightmare (often misremembered as "The Nightmaretaker") with Touhou Project character Youmu Konpaku. The subtitle Akuma ni Tsukareta (悪魔に憑かれた) suggests demonic possession as a central mechanic.

No verified gameplay footage exists; references appear in anonymous imageboard archives and lost media wikis.

As an eroge (erotic game), the content is focused on corruption, hypnosis, and degradation.

Alleged mechanics include: