Mori no Kioku

Takumi and Jun are two students who find an abandoned bomb shelter in the forest behind their school, a secret they keep between them. One day they hear, noise, and upon investigation find a secret lab within the shelter, and a young boy, Tsukasa, being held prisoner there. They decide to try to free Tsukasa and try to solve who is responsible for his kidnapping. They suspect it is someone within their school that knows about the place, and decide to hide out at the school at night to see if they can find their answers...