From 87 Percent Translation:

Reiji Saeki living in the north eastern countryside town lost his life in an accident during summer vacation. .....But before he knew it, a mysterious ball of light exist in front of his eyes in a world of whiteness. Being a magician from a parallel world, that ball of light is looking for someone qualified to inherit the magic they had created to prevent it from being lost. Reiji who took on that suggestion lives in the parallel world, Elgin, with a new body and powerful magical power.