You could edit the font if its' terms of use allow it. Although don't ask me how, since I usually just download a font if I need one
@TheoAllen MSGothic, MSMincho, MSPGothic and MSPMincho support them. Most fonts we know and use (Tahoma, Arial, Times new Roman) don't support them. But I'd recommend getting another one from the internet if I was searching for one that supports hiragana, because MS fonts look really ugly. They are edgy, not smooth. Not good for an rpg maker game.