My Gu Can Cultivate on Their Own - Chapter 245 - Second Half   

A master assassin transmigrates into an interstellar era.

Mo Ran felt that taking Chu Wanning as his master was a mistake.

His Shizun was just so similar to a cat, while he was like a silly dog.

Dogs and cats were biologically different. The silly dog hadn’t originally intended to put his furry paws out towards that cat.

He originally thought that dogs should be with dogs, like his senior brother, who was beautiful and docile, like a cute Japanese Spitz. They would look so good together.

But after dying and coming back to life, after living two lifetimes, the one he’d brought back to his den both times was that snow-white kitty Shizun that he didn’t even have his eye on at first.

- Description from Novelupdates

Within the Immortal Realm, there were nine thousand major realms, with three thousand at the top, three thousand in the middle, and three thousand at the bottom, along with countless minor realms.

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.