Sima Yi, the Thief of Great Wei

When he wakes up, Sima Yi, a grad student in history who has always slacked off, discovers that he has really become Sima Yi. Faced with a summons from Cao Cao, a mighty ruler of his age, he remembers the War of the Eight Princes and the Upheaval of the Five Barbarians that followed the Sima family's seizure of the throne, and breaks into a cold sweat. Usurp the realm? Sure! But I'll take over a strong, united state that can endure for centuries! He decides to use knowledge from beyond his era to assist Cao Pi and build up his strength, before finally claiming the whole realm for himself, with interest.