Yeah, I've tried to hold off and ressing, but I think I'm on my 3rd or 4th dragon rot.
I didn't want to go to bed angry, but it's getting late and I couldn't kill that purple ninja. Moved onto the next sub-boss who is giving me just as much trouble.
Did everyone finish Ashina Outskirts before moving onto Hirata Estate? Once I got the bell, I abandoned Ashina.
So, I got him down to like 25% health, fire is strong against him, so I was throwing oil then using fire. I'm going to tackle him again later.