Margrave’s Bastard Son was The Emperor summary:
“An emperor who died unjustly becomes a wretched bastard son!” Ian, a wizard of the Bariel Empire, became emperor at a young age, but was imprisoned due to his nephew’s rebellion. However, he was saved by the wizard Naum using forbidden space-time magic. This magic leads Emperor Ian 100 years into the past, where he possesses Bastard Ian, the illegitimate son of the Margrave family that went extinct 100 years ago. Bastard Ian is about to be taken hostage by the barbarians! Ian is about to get caught up in a bloody conspiracy!!!