「If it can be true——a happy, end」

Strange lifeforms known as 「demons」which took people’s lives in the past are rampaging, bringing chaos to the current world.

In order to fight with them, half-demons known as 「dance princess」 were created by the people. In addition, by worshipping the sacred Sakura tree to seal the border with the other world, the appearance of the demons gradually decreases.

But as time goes on, the sacred tree was eroded by impurity from the demons.
Demons are starting to appear again due to the seal being worn off.

Then, the people successfully created a half-demon who bears the curse of immortality. By offering to the 「gods」, the impurity and himself was sealed in the land and balance of the world is brought.

800 years has passed by since then.

Being the one offered to the「gods」,
the boy carrying the curse of immortality —— Mikoto.
Battling as a「dance princess」,
the girl who seal the demons at the cost of her own life —— Sakura.

A boy wandering in his own solitude, and a girl searching for a place to spend her final time.

This is the story of their last 29 days of meeting and spending time together——

[Translated from official website]