If I have one wish in the world, that would be the characters from the Koei Warriors franchise (Dynasty, Samurai, Orochi, etc.)
Think about it...
There is a Sengoku Basara version of Yukimura and Masamune, but there is no Samurai Warriors version of these two (along with other characters).
There is a Three Kingdoms-based fighting game called Sango Fighters in which you play as historical characters such as Zhao Yun, Lu Bu, Xiahou Dun and Guan Yu. However, what I want is the Dynasty Warriors version of the characters I mentioned, as well as others.
Speaking of DW, how about Zhuge Liang, the Sleeping Dragon? He only exists in Dong Dong Never Die, but not in Dynasty.
As for Warriors Orochi, I have not much knowledge about that series (I only played one) but I guess it could start with Orochi and Daji, who appeared since the first Warriors Orochi game. Speaking of mystical characters, I suppose Nuwa, Fuxi, Taigong Wang and others could fit in well.
For a character already fit in the fighting game, Dead or Alive 5 once have SW's Naotora Ii added in the roster as DLC. If you don't believe me, look up on Youtube and analyse her movesets. Or y'know, get the game and buy the DLC yourself. I don't know, you do you.