PayPay is one of many competing services. From August they're going to stop letting you use other credit cards with PayPay; I suspect (and frankly hope) that will hurt their adoption a lot.

There are others but I've never seen anyone actually use them. Maybe LINE Pay, and people spending d-points.

And while personally I'm going to be affected by their change in credit card rules, everyone I know uses it with cash to get in on their gatcha mechanics. Everyone is surprised when my payment doesn't have the "roll" to see if you won anything.

I've used Line Pay and AU Pay (indeed if we're talking about person-to-person money transfer I've seen more of that with Line than anything else, although of course it's the same company), and I think I've seen the Aeon one get used too. If you include the various tap-to-pay systems then there's a whole lot more.

France has Paylib which was created by the banks and is used by nobody because it’s an incredible PITA to use.