Who is the dead? In the spring of 1998, in that class at the school, there is a "secret" that must not be told to anyone. Sakakibara Koichi, 15, who has transferred to Yomiyama Kita Junior High School, feels uncomfortable in the atmosphere of the class, which seems to be scared of something. You'll be able to find out what's going on in the world, but you'll have to be careful not to get caught up in it. ・・・・・・ What on earth is happening in this "world"? "In the meantime, we're going to take a closer look at the history of the world, and we're going to be able to see what's going on.
Kouichi is attracted to a beautiful girl with a mysterious presence, Misaki Mei, and tries to make contact, but the mystery only deepens further.
And then the unexpected disaster happened!