Yoshiko a hard working high school student is always taking care of others. Despite studying hard for herself, she still finds the time to take class notes everyday and deliver them to her home bound, video game playing, childhood best friend who has not appeared in school for quite awhile. One day on her way back from delivering the notes to her friend, she notices "black snow" falling from the sky. Confused she asks her friends Miki and Kiriko if they had seen the snow too and having not seen anything, her friends assume she has been overworking herself.

Yoshiko who also regularly helps out a reclusive uncle, will one day bring her friends along to help planning on a doing some karaoke afterward. Thanks to the appearance of the black snow an ominous event happens and things keep getting stranger and stranger...