Time Travel: Starting from Bearing the Infamy of Killing a Master

Time travel + system + low martial arts + tactics + low magic + unknown era + historical military commanders, a hodgepodge of original military commanders. As an investigator, I traveled through time before I died? Didn't you expect that you can encounter strange and weird things while traveling through time? This is not the dynasty I know at all. Where did this damn thing come from? What! If I go down the mountain to collect some medicine, will I become the murderer of my master? It turns out that there is a bigger conspiracy hidden in Master's death? I want to find the truth! I want to use the system to change my life against the odds!