In 2016, a huge cocoon suddenly appeared in the metropolitan area of Japan. Several months have passed since the first confirmation, and its true identity has not yet been determined. People call this unknown cocoon a Phenomenon. The only thing that can be understood is that people absorbed into the Phenomenon will start to go crazy and kill each other. The Japanese government, anxious about this, organized a special force to deal with the sudden appearance of the Phenomenon. The Ministry of Internal Affairs and Communications Information Management Bureau has jurisdiction over the Special Attack Team of the Special Strategy Team of the Expanded Reality Group, also known as the Expanded Girls Trio.