filthqueen666 少し日本語を知っています。[I know a little!]
I’ve been going to classes and studying on my own for about a year now just as hobby. I really enjoy it, but it’s quite a time commitment and I’m still much better at reading it than speaking/understanding someone speaking it at this point. Learning a little before you go will definitely help you enjoy things more, but it’s not essential to get around, especially in Tokyo or Kyoto.
You can teach yourself hiragana and katakana through Tofugu, which you’ll need to ultimately learn kanji:
https://www.tofugu.com/japanese/learn-hiragana/
https://www.tofugu.com/japanese/learn-katakana/
Katakana is basically the character set they use for loan words, so learning that more or less will let you read English in code. A lot of bar menus are written in katakana, so you’ll see stuff like マティーニ (“ma-tei-ni”/martini) or ビール (“bii-ru”/beer). We were in a basement bar with no cell service at one point, so no one could use google translate, and I got to swoop in and act as translator…despite barely knowing any grammar. It felt awesome!
Anyway, holler if you want any recommendations for what to prioritize or good learning resources!