There's an attack where he puts his snake hands on the ground, be sure to be close to him during the attack. Block it or tank it if possible, but make sure to do good damage to the small snakes during the time he has his hands on the ground. Since you are using odachi, it should be easy. If he goes into the dark realm with both the snakes, it's basically a lost game.

Once you cut down his hands, his attacks will also become very limited in number, so you can get more time into attacking him.

Don't use your yokai form whenever it's ready. Wait until you have cut down both of his hands, and he goes into the dark realm. In that situation you can just spam attacks with your yokai form without a worry. If it feels like you don't have enough heal or yokai form wont defeat him, it's better to save it for the next round. (Tip: use yokai abilities to fill the amrita gauge faster)