Isn't Japan mostly cash-based? Seems like an interesting location to expand to.
Online, users are extremely comfortable paying electronically. You have to remember that paying via mobile was a thing here several years before the rest of the world, so people have had longer to acclimatize.
As a reference point, Japan spent around $8B via mobile phones in 2006 (i.e. before the iphone launched).
Similar deal with NFC payments. They launched here in 2004, and were fairly widespread by the time smartphones arrived. It used to be very common for people to move "up" to a smartphone and then be surprised to find out how many features they'd given up.
On the other hand I prefer to, difficult to find d out what's wrong when the stop workers speak Japanese and I don't haha