Suzaku

Technological progress has now reached the point where time travel experiments can be carried out. Suzaku is a teenager born and raised in feudal Japan, Heian period (794-1185). You are the highest-ranking general in your country. Something went wrong during a time travel experiment and a person was transported from the past into your timeline. The government of course wants to keep this under wraps, but since you are the only one in the military who understands Classical Japanese, also known as Late Old Japanese, and because your parents are historians, the boy is handed over to you and told that you can do whatever you want with him want.