Infinite Ladder - 666/7

This story takes place in a post-post apocalyptic world, hundred years after the nuclear war that destroyed the world.
A Human, gained Enlightenment, long ago, making sun her home, and the light of the sun fell on the world, turning the hell into paradise, for those who were left.
But at night, one one side, there are those, who were left behind, the animals, dead, and much more, twisted and merged, having turned into monsters, dead yet alive.

In such world were born two, at the same time, but one at day and the other at night.

This story is of such two children, fated to meet, yet one is impossible to reach. Will they meet? Will they save...this dying world?

Tags - There is No Yuri, Yaoi, Nrt, or anything like that. It's simple.