Not OP, but I traveled through Japan with a few friends before the pandemic and none of us speak Japanese. It's true that almost no one there speaks english. However, everyone we've encountered (especially the people working in the service industry) was super friendly and tried their best to be helpful. The public transport system is thought out and labeled very well, even in english + it plays well with Google Maps, so navigation was never an issue.

One thing that I didn't expect (although it makes perfect sense) is that OCR of Japanese writing is very bad compared to what we've got used to. Aiming a phone with Google Translate at some sign will often produce total garbage. You can attempt to transcribe the kanji with your finger and that usually gives better results, but is tedious and difficult (since the order of strokes matters and you have no clue about it). We've quickly learned a few crucial kanjis, e.g. 出口 for `exit`.

A tip for the restaurants that only offer japanese menu with no pictures: open the listing in Maps, browse through the photos and show the waiter a photo of the meal you would like.