Koi-Koi

Koi-Koi is a gambling game which is unlocked in Chapter 10 of Yakuza 0. This is another game which is likely to confuse Western players at first -- the cards will be wholly unfamiliar to most, and the combinations and gameplay won't be obvious at first. The in-game help menus for koi-koi are a bit obtuse, to boot. I won't go into all the details here, since it's described pretty well online at a few sites, but the one that was most helpful to me was this page at lovethynerd.com, which had a nice graphic with all possible cards, with the "special" ones labelled. I modified that image slightly to have numbered months, so that they're easy to match up with the "current month" number while playing the game in Yakuza 0:

Yaku/Sets

Having a nice visual reference for all the cards was certainly nice, but the other thing I'd wanted to have was a clean visual reference for which yaku/sets were possible. I did find a reddit post which put one together, using ingame screenshots, but as I mention above, I wasn't fond of the in-game help screens. For one thing, they only show one possible combination of cards which can complete the set, rather than showing all that would match.

So, using the card images from above, I put together my own, which shows all possible cards which can make up one of the sets. For each of the yaku, I've labelled how many you need in order to complete the set, but the card lists will show you all of the possibilities. Note that the yaku list at lovethynerd.com that I linked to at the top describes these slightly differently than Yakuza 0 does. I'm honestly not sure, in those cases, if the Yakuza 0 in-game docs just omitted them by accident, or if the Yakuza 0 version differs slightly from the version described at the other site. The differences are pretty slight, though.

The "Season" cards listed there are just an example showing what the valid cards would be for the first round (Month 1).