Bloodhound’s Regression Instinct is a Manga/Manhwa/Manhua in (English/Raw) language, Action series, english chapters have been translated and you can read them here.
“Yan,” the protagonist, was brainwashed by the emperor and lived as his puppet. After finding out he was being played by the emperor, he planned to seek revenge, but collapsed due to the emperor’s might. He thought he had died, but when he woke up, he realized he had regressed to the time when he was a recruit. Whether to seek revenge on the emperor or to find his family. The choice lay in his hands.