User blog comment:B214/Question and Answers 2/@comment-24098614-20140309015414/@comment-1359322-20140309023610

Just one thing and it's perhaps the main reason why Ishibumi chose to write Cao Cao.

The Original Cao Cao was viewed as a villain because of his desire to conquer China, unlike Liu Bei or Sun Quan, Cao Cao wasn't truly evil, he just did what he think was best for the future. As to why Cao Cao was viewed as a hero, that is because in the past, China has a discrimination system where only the rich are viewed highly while the poor are ignored like trash. Cao Cao broke that system and opened up his army, government jobs and schools etc to all citizens equally regardless of their status just solely on talent. That's why Cao Cao had the largest army among the three kingdom, as well as having truly loyal followers. That's also why he was a more successful king than Liu Bei that keeps promoting peace while maintaining the same discriminating status.

In a sense, that's why Ishibumi chose to write Cao Cao over others, he just seems to be the best choice to have as a leader of a group of abandoned Sacred Gear users.