A lot of the recent “cheapness” of Japan is due to the drastic drop in value of the yen. Two years ago these workers would cost like 50% more.

Japan also has better worker protections, so hiring and firing is more difficult I imagine than India. One way I’ve heard American firms fire is to force employees to relocate to another Asia office with more lax protections. The employee gets relocation costs covered but if they get fired within a year they have to pay those expenses back. The employee knows they’re just going to get fired so they quit.

On top of that, English is probably not as good. It’s taught in schools but you don’t need it for most jobs.