One day, Shiori Maezawa, an ordinary high school girl, cracked her smartphone while falling down a staircase. As she wakes up, she finds herself in a deserted, parallel world that looks like Yokohama. When she looks at her smartphone, she finds a photo of herself that she doesn't remember posting on social media. What’s the source of this mysterious post? Will she be able to escape from this strange smartphone labyrinth? (Source: Official Site, translated)