Max out your prayer beads/ attack, I personally defeated him on my 2nd attempt which I attribute to my max hp and attack allowing me to last longer, learn, make more mistakes, and punish better. I really hope this can translate to inner isshin.

PRAYER BEADS, FOOL
The amount of health you have has to be the biggest factor in the difficulty of this fight. I've done loads of runs where I collect everything and I gan get him in one try. Now I'm trying a "boss rush" run, just ignoring anything that's not necessary and out-of-the way. I'm trying him with 3 necklaces, seven heals, and minimal strength (skipped headless ape, lady butterfly, Owl Father, and DoH). It's wayyy harder than my charmless run where I maxed health and strength. You stumble once during one of those long combos and that's a life.

With this much of a difference, I believe both those who say it's not bad and those who say it's near-impossible. If you're really struggling and don't have those beads, go back and get what you can.

if you've truly internalized every lesson the game teaches you he doesn't come off as difficult as some people make him out to be (still pretty damn hard), if not he feels crushingly brutal. I had more attempts vs the lone shadow long swordsman's than Isshin, I refused to learn to cheese the lone shadow or any of the other early game bosses I struggled with and the feeling of becoming so much exponentially better at the game was extremely satisfying. the entire game builds to him, he is the skill check of all time.

Isshin the Sword Saint is unquestionably the epitome of a boss fight. Given it comes from the Magnum Opus that is Sekiro is no surprise.

However he is also the most difficult boss fight in any FromSoft game likewise Sekiro being the most difficult of all of their games.

All in all this man is a force to be reckoned with make no mistake of that

For a moment I felt like captain america when I used umbrella to block his gunshots.

My first and only playthrough so far, I got all the way up to this boss when Elden Ring was released. Sadly, I couldn't resist the temptation of a new game. Several playthroughs later, I'm tired of Elden Ring and now I have to start at Isshin to finally complete this game. I've also completely forgotten how to play Sekiro. Wish me luck - I'll need it.

IKUZO SEKIRO

imo the greatest boss fight of all time

The 2 biggest tips I can give:

1: be super agressive, always attack him when you can, and stand your ground and deflect his attacks. If he creates distance, run after him immiediatly

2: Lazulite axe

Just beat this guy for the first time, such a good fight.

Although, I almost regret using the lazulite axe on him, it obliterated his posture and honestly made the fight kinda easy, he was down on my second try