(edited to be correct)
US keyboard layout is used for Japanese install.
This happens on both netinst and Live install.
On Live install, only Japanese (Anthy) as Input Source is available though, apparently keyboard layout is US.
On netinst, two Input Sources are configured. English and Japanese (Anthy).
This behavior looks like a regression. On f38, it was Japanese and Japanese (Anthy) and the keyboard layout was jp106 or something like that.
This behavior looks like a regression to me.
Steps to Reproduce:
1.Install Live with Japanese
English and Japanese (Anthy) is available at Input Source
Japanese and Japanese (Anthy) should be available.