A Certain Dark Side's Item

A massive "academy city" located in western Tokyo.

In this city, with a total population of 2.3 million, approximately 80% of whom are students, a special curriculum for developing psychic abilities is implemented, and the students' abilities are evaluated on a six-level scale from "Level 0" to "Level 5".

Boasting scientific and technological advancements far surpassing common sense, this dreamlike educational institution provides everyone with scientific abilities and allows them to live in peace—but behind this tranquility lies a "dark side" organization that undertakes dirty work that is never revealed to the public.

"ITEM" - an elite unit composed of four girls.

Kinuhata Saiai, who can freely manipulate nitrogen to provide an impenetrable defense.
Frenda Seivelun, who uses explosives and traps to toy with the battlefield .
Takitsubo Rikou, who can read and track the faint powers emitted by ability users.
And Mugino Shizuri, one of only seven "Level 5" in Academy City. 
Then, a fifth girl appears before them.
Their encounter with her leads the "items" into a new darkness.

This is a story depicting the daily lives, bonds, and deep, profound darkness of girls with rather unusual abilities, steeped in violence, cruelty, and depravity.