Teogonia

神統記

Humans fight to protect their land from invading demi-human tribes in relentless battles. As his world is engulfed by intense warfare, Kai, a village boy from Lag, joins the fight to defend all he knows. After Kai’s comrades fall one by one and he’s injured, he suddenly recalls memories from another life. A fantasy tale unfolds as a village boy explores a world of magic, mystery, and heroism.

(Source: Crunchyroll)