The character who returned 10,000 years later is Oh Kang Woo, the main protagonist of the manhwa (Korean comic) titled "Player Who Returned 10,000 Years Later," also known as "After Ten Millennia in Hell." Oh Kang Woo fell into Hell and spent 10,000 years there, devouring countless demons and becoming powerful enough to make the seven princes of Hell bow to him. Despite having great power in Hell, he was determined to return to Earth, which he finally does after ten millennia. Upon returning, he finds Earth drastically changed, with dimensional gates appearing and the world resembling an MMORPG where players hunt monsters to survive. His powers are initially sealed, and he must adapt quickly to this new reality

. In summary:

• Name: Oh Kang Woo
• Story: Fell into Hell, spent 10,000 years gaining power
• Returned to Earth after 10,000 years
• Earth is now a dangerous place with dimensional gates and monsters
• Needs to level up and survive in this changed world

This is the core premise of the manhwa "Player Who Returned 10,000 Years Later"