I Became a Legend After My 10 Year-Long Last Stand.

Luck, the S-rank sorcerer in a hero’s party, stays behind when endless demonic hordes threaten to wipe out his companions. He expects to buy Eric and Goran enough time to escape, but the battle refuses to end. Luck holds the dimensional rift alone for ten years and eventually defeats the Demon King himself. When he finally returns, only a fraction of that time seems to have passed for him, while the world has spent a decade mourning him. His friends have grown older, and stories now celebrate Luck as the great hero who sacrificed his life to save everyone. The fighting has also left him looking younger, giving him a way to avoid the legend attached to his name. Hiding his identity, Luck starts again as the F-rank adventurer Lock, rejoining old comrades and meeting new ones without revealing the power behind the rookie.