I'm sorry but this does not solve my issue. I am already able to switch to japanese with a hotkey. The issue is that once I have switched to japanese there are then two "modes" that the japanese keyboard can be in, one for writing in romanji(while still having japanese selected as a language) and one for writing in hiragana.
I have no need to write in romanji on the japanese keyboard but when I switch to the japanese keyboard it will sometimes be in "romanji mode" which then requires me to click the hotkey ALT ~ or a small button in the corner of my screen with my mouse, in order to swap back to hiragana. This slows down my flow of typing when I need to switch between languages.
What I want is to change that hotkey, the one that is ALT ~ . Swapping between languages already has the hotkey ALT + Shift which is no problem.