In the floating city of Aelthar, suspended above a bottomless void, peace has reigned for thousands of years enforced by a long-forgotten legend. When two ancient worlds once warred without end, a man named Yohei rose with the power to destroy both. Instead, he gave them a choice coexist… or vanish.

Sin Kerika, a quiet 17-year-old boy, lives an ordinary life of silence and solitude until a knock on his door brings back a girl no one else remembers. If he forgets her, if he stops speaking to her… she disappears forever.

But her arrival is no accident. A hidden force has awakened beneath the city one that seeks to shatter the peace Yohei forged. In this world, power comes with a price. And you don’t get to choose what you lose.

As Sin is dragged deeper into a war no one sees coming, he will be forced to make a choice that changes everything.
To protect Yuki…To protect the world…He must give up the one thing that defines him.