The date: 2015 AD. The Angels' assaults on Tokyo-3 have increased in its ferocity. In this city, three young girls upload their latest song onto Nico Nico Douga. Haruka Ishii, Izumi Taniguchi and Ayako Matsuzawa. The three girls were juniors in Tokyo-3 Municipal Junior High School No. 1 and they were active on Nico Nama (Nico Nico Douga's live streaming service) as the musical group, Impacts. But with Ayako evacuating the city in order to avoid the Angels' onslaughts, the group was to break up after releasing their latest song, A Sentimental Hunch. Haruka, Izumi and Ayako were about to live their lives, separated from one another. Realizing she would be left behind, Haruka makes a proposition to Izumi. And now, another Angel is about to wreak havoc on Tokyo-3...