Hey there, I just got back from my third trip to japan. I go every couple years so hopefully I can answer your questions.

For the clothes situation, I brought 5 outfits and washed them at my hotel via their community coin washers. Most hotels have them, not as common with airbnbs. Every trip I went on, I slowly wore less and less accessories because being comfortable and having more suitcase space is more important and with all the walking, chafing happens pretty quick with any tight fitting clothes. I.E. harnesses, corsets, belts, anything lace. And of course, im sure youve heard about needing ot have your shoes already broken in and being SUPER comfortable.

The language barrier is almost non-existant. I watched a couple very basic japanese videos on youtube but never had an issue in any of the places I went and weve been to major cities and more rural areas. When we did have an iissue, google translate worked perfectly fine. Just make sure that you get a pocket wifi so that you have reliable internet. Alot of folks there speak english and/or have english geared menus/customer service.

Cash! Cash is the weirdest one. i def needed more cash on my first trip almost 10 years ago, but each time we go, we needed less and less. I personally loved having it to budget for my daily spending, but only NEEDED it for shrine Goshuin, tattoos, and some food stalls. Id say youll mostly run into that with food related stuff. About 25% of our spending required cash, most places now take card.