You are amongst the survivors of the infected PJSK worlds. In each SEKAI, there's at least one or two parasites who are wandering. The parasites and the survivors are;

Survivors: Akito, Shizuku, Rin, Kanade, Saki, Rui, MEIKO, Nene, Shiho, Haruka, Kohane, Mizuki.

Parasites: Miku, KAITO, Luka, Tsukasa, Honami, Ichika, Airi, An, Toya, Emu, Mafuyu, Ena, Len, Minori.

Good luck, you are on your own...