Okaasan Akuma Desu

Almost half of Japan has been wiped out from an unknown cause. There is one girl who wakes up in the middle of the abandoned city Osaka. The girl Fuyuki Sugiyama, has no knowledge of what happened and where she is, what she is. There is an unknown force, constantly pulling her towards an aquarium that is located right next to the ocean. She feels the need to go in there, she has to go in the aquarium. In the aquarium the marine life is thriving but there's no humans to be seen. Fuyuki finds an abandoned subway, and a gate to the train opens. Fuyuki boards the train and discovers that there is a Yuki-Onna, so she has to go through the train and can’t turn back.

There Fuyuki goes through various train carts to find out the truth of what happened. While in the train carts, Fuyuki faces many challenges as she encounters many different yokai, deadly Japanese entities and spirits. Play as her and uncover the truth of what she is and what happened to Japan.