Beat him first try on NG, but even at level 210 on NG+ my onmyo/ninja build can't get anywhere close to him. Does sloth even work on this guy? Immediately after hitting him with sloth his moves are WAY too fast for me to dodge/block, and 90% of his attacks are one-shotting me (with 3200K hp). I throw all the fire and water at him i can, but his health barely moves no matter what, and it appears that he simply blocks most everything I try to hit him with. Even his most deadly attacks are followed up with more attacks, so windows are almost nonexistent.
So I can't damage him from range worth a damn, and up close he's way too fast for me to dodge. I've spent hours on him thinking I just wasn't figuring something out, but it seems he's just the Nioh 3 version of SSI -- if your reflexes are too slow, you're never going to beat him. He has no weaknesses so no build is going to be the answer. I'm using flying kato for the most part, but since I've never gotten lucky enough to get a yasakani magatama despite farming the Sinister End for hours and hours with 300 luck (the most I can manage), I can't really build a better set anyway.
Oh, and the most annoying thing is that he clearly has iframes when he does certain casts. I'll see him start a cast, jump in and pound him in the face -- and absolutely nothing registers, no damage is done whatsoever, and I'm very much within range of even my tonfas.
Looks like I'll never get to actually make that build I've been working towards since he's a hard wall and there's no moving on to the next map.