Why is there a English (Japan) keyboard in iOS?

I'm looking at the Keyboards menu in Settings, and there's a US, UK, Canada, Australia, and Singapore keyboards, which make sense because those languages are of course spoken there, but there's also an English keyboard for Japan? I can't really think of why Apple chose to give Japan a keyboard for a language that is neither and official language nor is widely spoken there at all. There are far more English speakers in many other countries that do not use it as an official language but Japan is the only non-officially-English-speaking country that has an English keyboard on iOS. There doesn't really seem to be much of a difference from the others using it. I know this isn't a very important question but it just had me very curious. Thank you!