Read The Ashen Snowfield hentai manga on hentaidexy.
summary for The Ashen Snowfield :
The world didn’t end with a bang. It was a flash of light bookended by a long, endless freeze that covered the landscape is white snow. Kindness and compassion were replaced with struggle and the ruthless will to survive. And then, there are the Ashen. New beings with abilities beyond that of normal humans, giving them an edge above all others in the frozen wasteland. In this war, there are no victors, just survivors.