Ihoujin, Dungeon ni Moguru - Chapter 125: The Forgotten Rossian I & II

Zhang Ruo Chen was the sole male heir of one of the nine emperors of the Kunlun Field. Ruo Chen’s father was known to all as the “Enlightened Emperor”, however Ruo Chen didn’t just leech off his status as emperor’s son. He proved himself to be a dragon amongst men, possessing a heaven defying body, and managing to cultivate to Greater Perfection within the Yellow Horizon Realm, at just the young age of 16.

But even though he stood at the summit of the younger generation and had a boundless future, he sadly died at the treacherous hands of his own fiancee at a young age.

Reincarnated 800 years later in the body of a young boy who shares his name, he found out his former fiancee already unified Kunlun’s Field and built the First Central Empire, and was now known as Empress Chi Yao… Empress Chi Yao—Her Majesty governed the mortal world and enjoyed prestige in all directions as well as an eternal life.

Zhang Ruochen stood outside of the Imperial Ancestral Temple, looking at the statue of Empress Chi Yao, and the flames of hatred burned in his heart. “After I practice for 13 years, I shall send the empress to her doom!”

- Description from Novelupdates

The handsome Emperor falls in love with a Knightess! Knightess Poliana loses to the Acreian Army and despite her struggles to survive in a male infested military, she is now about to die. But then, the young king of Acreia sees her efforts and tells her: "I have a dream, I wish to conquer the world and become an Emperor, would you like to join me?"

The eldest son of the assassin aristocrat Tuatha Dé.

The skill, experience, knowledge of the previous life, magic, all of which grows his power as an assassin.

Excellent assassins pass through. He was usually admired as the ideal lord, and behind it wielded a blade as an assassin aristocrat.

Gu Ting Yu is a veterinarian with a fear of animals. Haunted by the same nightmare all these years, he is desperate to find out the reason behind those dreams. He then travels into a fantasy realm by fate, entering the Palace of the Twelve Sacred Beasts.