Does unlocking Sai-Fung require beating the game first?

I know you need 100 chapters on normal difficulty but I've seen no site stating if this has to happen after you beat the game.

I haven't beat the game as I'm on chapter 12 still and on normal difficulty. What if I complete the 100 chapters now repeating stuff over and over again. Can I unlock Sai-Fung before doing the other chapters?