Gankira

"Abnormals" - those that exhibit inhuman abilities and interact with the supernatural hidden from the public eye.

Struggling to live up to the legendary legacy her adoptive father left behind, Jujika, a young investigative officer, is forced to help participate in a brutal bounty hunting system with a ragtag team of Abnormals in order to live.
While chasing a certain bounty, however, she comes across a cursed item that forever changes the course of her life: A monstruous gun summoned from a bullet casing, containing the soul of a serial killer that never existed.

Source: MangaPlus for Creators