I actually went to an university in the Tokyo area as part of a university exchange program, so I don't know much about language schools, I'm afraid.
Visa shouldn't be a problem, as long as you can get a "Certificate for Complexion of Registration to the ERFS system", which can be delivered by any government-recognized institution or organization based in Japan. Look up schools that offer such a certificate, there should be a good amount of them. Then, as per Japanese customs, get ready for the endless and repetitive paperwork to be filled in, a certain amount of back and forth, and you should be good to go. Also, you're most likely going to have to be vaccinated at least 3 times. They don't joke about that.
I really didn't expect to talk about Japanese language schools in HC2's game thread honestly, that feels a bit weird^^
Her in-game pixel art model doesn't have a sword, although she has an armor outfit as well that she wears for a good part of the game. I wanted to have the sword in the banner to really emphasis her role as part of the military.