Survive in the parallel world, please! sitpwp

In a world where the human race is bound to be annihilated, six heroes are summoned with the sacred mission of saving mankind from extinction. The task of leading them in their crusade falls upon the shoulders of a single amnesic and weak man forsaken in the wilderness alone without any means of survival.
Join Ryu's adventure in this slow paced journey submerged in a fantasy world where he'll meet friends, enemies and love interests who will discover this brand new world along with him.

So, survive in the parallel world, please!