First thing I notice is that when your Hagakure is almost off CD your Kenki was at 50, you did not use it on Shinten the whole time, you could have spam it all on Shinten and then 3 Sen Hagakure to get Kenki back. Guren also sits there for quite long when it's off CD and you have enough Kenki to use. You did not reapply slashing debuff for a few seconds as well. Jinpu drop off for a few seconds at the start.

General rules of thumb, keep buff and dots up at all time, use Guren and Hagakure off CD, spam excess Kenki on Shinten unless you need to save it for Guren that will come off CD soon. Float your kenki around 20, that's how much you need for Kaiten.