A direct, or fair, fight here is crazy town. But I figured out a way to abuse the stairs at the back of the arena. Make your way over to the stairs, climb up, and then fall off. Yukimura will follow and fall down, giving you a few easy hits. The goal here isn't damage, it's to drain his ki. A falling attack from the stairs will significantly drain his ki but is riskier.
Once his ki runs out, his annoying summon goes away. Then you can get a powerful hit off on him while he's stunned and even keep going until he summons again.
The wind stage is similar and the stairs have the added benefit of messing up most of his attacks. The large AoE doesn't even hit you if you're above it on the stairs! The same is true for a lot of the projectiles. This stage can be more dangerous because he's quicker, but the damage wasn't as bad as the fire to my character.
Also, I have fire stop and wind stop talismans for when he summons in help. And this was my first attempt at this strategy and it still worked really well! Keep at it!
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