For example, Yahoo Japan (still more popular than Google Japan AFAIK) pays collage grads $36k a year starting salary. I think USA Google Interns get ~3x that.
I know it's just one data point but it's not far from the average. For Sony, Sharp, Panasonic, Canon, Nikon, NEC, Rakuten, etc it will definitely be in the same ballpark. You can probably get 2x that if you have 10 years experience but if you're over 35 you're considered too old to code by many companies.
There are exceptions like maybe Mercari as they are doing well. And western companies, Google, Amazon, Goldman Sachs, pay well.
I have no idea if this is why but I'm guessing one reason is they have a captive market. If your only language is Japanese you can't work anywhere else in the world.