KOROSU-HITO: the one who kills

Young Akari Kamiyama, a nomadic assassin, gets her first job that involves killing an actual demon. She's never done this before, but it turned out to be surprisingly easy. However, the demon wasn't as weak as Akari naively assumed. After being poisoned by the demon she finds herself in the butterfly mansion, where she and other demon slayers find out about her formerly secret ability to resist poisons, which spikes the interest of the Insect Hashira - Shinobu Kocho.

After training under her guidance for several months, Akari's past remains a mystery to her comrades, but her remarkable progress during training raises questions. To prove herself, Kamiyama gets sent to her first official mission - to infiltrate a criminal organization that is rumoured to have strong connections to demons. While undercover, she unravels a mystery regarding her family, that she never thought to hear about again. Meanwhile Kocho starts to investigate Akaris past, trying to figure out what secrets hide behind her new student.

Will Kamiyama be able to find her way out of this tricky situation? What will she do about her newly found family? Will she be able to hold her position as a demon slayer with all the secrets she's keeping about her past?