This one is simple. Choose Asuka, and go to Hanzo Academy 1-1; you'll be fighting against wooden Training Dummies.
Defeat all of them until 1 is left, then lock onto them. They have 3 attacks they will use:
1) A wind-up left-handed swing
2) A wind-up right-handed swing
3) A running shoulder charge (When it hits depends on where they are in relation to you)
It's fairly easy to grind this out.