Jaeanggeum Necromancer Euntoehaneun Beop

Han Ji-Hyeok, the necromancer who saved humanity on the Seron continent. He returned to Earth to live a peaceful and happy retirement, but his retirement plans went completely awry from the first day. The protagonist, Han Ji-Hyeok, who is now twenty, is summoned to the Seron continent by a wizard named Teros and lives as a necromancer. After many years, Ji-Hyeok defeats the Demon King and returns to Earth, but due to the law of causality, the Earth he returns to is not as he remembered due to the Gate outbreak and monsters. To make matters worse, Ji-Hyeok has lost the gold and silver treasures he brought with him, so he has no choice but to become an F-class Awakened and start making money. When will Ji-Hyeok be able to retire as he so desperately wanted?

(Source: Kakaopage, translated)