First time moving to Japan for language school (and possibly living there long-term)

Hey everyone!
So I’m 20 and planning to head to Japan to study Japanese in a language school. My end goal is to hopefully stay and live there long-term.
Thing is, I’ve never traveled before and don’t really know what to expect.

Any tip on what I should be ready for? Aything important or unexpected I should know before making the move?
I’d appreciate any advice! Thank you in advance!