Sage Monarch (Sage Emperor) - Chapter 1590: A New Age Begins!

A skilled but unfortunate modern-day assassin was killed in a freak accident. However, he soon found himself summoned to another world by an evil wizard, who had him possess the body of a boy as an experiment. After successfully planning the evil wizard’s downfall, he used the wizard’s body as a springboard to gain influence and power in his new world.

- Description from Novelupdates

This story is centered around the man named Yi Ji-Hyuk, who has spent 1000 years in a Medieval Western fantasy-like world before returning back to the modern-day Earth. When he returns, he finds that his home is facing monster threats, and that humans with superpowers have appeared to protect the innocent people of Earth.

The fiancée has betrayed, but how could she know that the man she looked down upon was in fact a prodigy with healing and martial prowess!

Yang Gang accidentally became the imposter heir to a wealthy family, with a beautiful older sister and a twin younger sister at home...