As you may already know, Ndesu is the boss for chapter 2-3.  I'm playing on PC and my fights with him always end in 3 rounds.

In the third round, he only has like 200-300hp left. I have successfully defeated him once (in 2 rounds) but having trouble replicating the result. Does this have something to do with FPS?

Any tips for the boss and for chapters 2-3 in general would be greatly appreciated. Thanks.