Also, have you checked out any Quick Codes for Kiwami? Equipping a War God Talisman makes most of the game very simple even on Legend difficulty. The main things that quick codes can't help with are minigames (except that you can add all items to storage which gives you "cheat" items for many gambling minigames) and the Climax Battles.
[CODES] Yakuza Kiwami (PS4)
I get some of my Yakuza games mixed up but for the Climax Battles, if you have trouble timing Tiger Drops, try either (1) dodging around like crazy while locked on, which if this is the right Yakuza game will build heat but I forget which fighting stance it works in, then use a heat move and repeat, (2) if that doesn't work, then the one I'm thinking of is just keeping your guard up the whole time, probably still locked on, and that builds heat so use heat moves as you can and repeat, and (3) whichever of those works, you can also use the Brawler fighting stance or whichever one has Kiryu acting all muscle-bound, then just using the move where he grabs and throws people (I think circle button, circle button), because you can stun-lock a single opponent that way. If you're not Tiger Dropping, then some of the Climax Battles can take quite a while with the dodge (or guard, I forget) method, but it's usually pretty safe and you heal a good bit between fights.