Entering his final year of school, Yukusue Arishi was leading an ordinary, peaceful life.
But one day, he begins to experience mysterious flashbacks which show him somewhere he doesn't remember. The flashbacks become increasingly detailed each day, eventually leading Arishi to visit the location he had been shown in order to find out the truth.

There, he finds a girl sitting quietly with her knees in her arms.

"I... must remain alone."

In the midst of extreme conditions, Arishi learns the meaning of these words.
She is a "monster" capable of swallowing up a human's presence.

――There is only one year left until Arishi's presence runs out.

Predator and prey.
Two people destined to never understand each other, yet they walk together for what time they have left in order to change their predetermined fates...

[Translated from NovelGame]