[Hack&Lube]

The reason I advocate for Yakuza Zero as the starting point is while Yakuza 1 was the first game released in the series, Yakuza Kiwami (I'll call it Kiwami 1) is very much the sequel to Zero rather than the mirror image remake of Yakuza 1 which is quite a dated game. Zero is basically a reboot of the universe with major improvements and the Kiwami games were purposely designed to follow its version.

Zero probably has to best-to-date (my opinion) secondary playable character and story arc in Goro Majima in the Osaka based Sotenbori map and Kiwami 1 and Kiwami 2 have some very emotional story points for Majima that were based off on Yakuza Zero exclusive material and won't hit properly if you haven't played that first.

Playing Kiwami 1 and 2 before Zero is very much NOT what they wanted to do storytelling wise as the content of Kiwami 1 and 2 is dependent on experiencing certain characters and moments in Zero.

But you could still finish Kiwami 1 (as it's quite a shorter game) and go back to Zero without hitting those points I mentioned IIRC because its more in Kiwami 2 that you revisit Majima proper.

If we are talking about release-date things, the tech used is also interesting. Zero and Kiwami 1 both share the same updated engine from the PS3 days but Kiwami 2 jumped to the Dragon Engine used in Yakuza 6 and newer games.

There's also the Judgement games which is another can of worms. The other crazy outlier is Like a Dragon: Ishin! (the 1800s Edo era one) which I played to death last month and was only localized into English last year. They completely rebuilt that game in Unreal Engine for the modern and first english release.