is a Japanese light novel series written by Kazuma Kamachi and illustrated by Nilitsu, which is a spin-off of Kamachi's "A Certain Magical Index" series, focusing on the women belonging to Academy City's dark side. ASCII Media Works have published four volumes since March 2023 under their Dengeki Bunko imprint. A manga adaptation with art by strelka has been serialized in ASCII Media Works' manga magazine "Dengeki Daioh" since October 2023 and has been collected in two volumes. An anime television series adaptation has been announced.




Media.
Light novels.
Written by Kazuma Kamachi and illustrated by Nilitsu, "A Certain Item of Dark Side" began publication under ASCII Media Works' Dengeki Bunko light novel imprint on March 10, 2023. Four volumes have been released as of March 7, 2025.
Manga.
A manga adaptation illustrated by strelka began serialization in ASCII Media Works' manga magazine "Dengeki Daioh" on October 27, 2023. The manga's chapters have been compiled into two volumes as of April 2025.
Anime.
An anime television series adaptation was announced during the "Dengeki Bunko Winter Festival 2025" livestream event on February 16, 2025.