Danganronpa Another Episode: Ultra Despair Girls Vol. 1
Also known as Zettai Zetsubou Shoujo: Danganronpa Another Episode. Manga by Hajime Touya and Spike Chunsoft.
Naegi Komaru, Naegi Makoto's younger sister, managed to survive despite being outside Hope's Peak Academy. There she meets Fukawa Touko, a.k.a. Genocider Shou. This is the story of their struggle to survive in a world full of despair.