The story begins with a dream the male protagonist has.
That dream was a very scary place, full of blood and the smell of rotting corpses.
Then he heard a voice: "We only have one year, when the month enters its 13th reincarnation. Then it will be the same as the place I lived before I came."
This is the beginning of March of the year.
Later he discovered that this was not just a dream.
He then goes with his friends to track down and solve these things.