Saltyman | Sekiro - Gyoubu Oniwa Boss Fight @SaltymanGaming | Uploaded August 2021 | Updated October 2024, 9 hours ago.
Gyoubu is fairly easy but sometimes he just runs around and doesn't give you a chance to hit him. Make sure you unlock the skill to attack during a grapple. It does good posture damage and will usually stagger him for a second.

I didn't even notice his weird extended sweeping attack was hitting me though.. Sometimes there's just no impact or any indication you actually took damage. It's a really weird attack. I think your supposed to jump and grapple to him to avoid it. If your close enough you might be able to jump kick off him.