Prologue [Journal]

In Musutafu, there is a forest. People called it 'Akumu no seishin'. It means nightmare spirit due to the civilians suddenly disappearing.

There were rumors about a creature that lives in the forest and the reason why people disappear. There were also rumors that this creature hates adults because there was a crime scene where a family went into the forest but the only one that came out were their children. Rumors about this forest was popular in the day but it soon got banned.
Heroes and polices made sure, no one will ever go back in the forest again.

Until one day, class 1-A heard about Akumu no seishin. Of course one of their friend disagreed to go there but they ignored him and entered the danger zone.

What will happen?