Not OP, but for the most part you can get around fine without knowing Japanese. In two trips across Tokyo, Osaka, Kyoto, Gunma, and Sapporo, the only transportation there wasn't any English for was a normal bus route in Sapporo; all other modes of major transportation, even buses in major cities, have English announcements and visual indicators.

For the bus I mentioned though, I just used Google Maps/GPS on my phone and guesstimated where to pull the stop request cord, etc.

For communicating with people, Google Translate works decently well. Obviously knowing Japanese would be ideal, and you should learn a few phrases, but it's ok to use Google as needed.

Can't speak for super rural areas, though.

I did something similar without knowing a word of Japanese. Google maps was super helpful as it knows everything about train schedules, platforms... It can be as easy as following the blue dot.

The rail pass gives you a lot of freedom since it allows you to hop on a Shinkanen without booking your seat in advance.

Definitely feasible, I didn't know any Japanese. There is English almost everywhere and many people are happy to be practicing their English with you.

Though I ended up learning some phrases while there so I could be more polite. The restaurant protocol really helped, and "sorry", "excuse me", "thank you", "hello", "goodbye" were all helpful.

The trouble with using only some Japanese is you will get a reply in Japanese and not understand it, so sometimes it's best just to be up front that you don't know it.

The trains themselves are effortless once you do your first one. You quickly learn the floor markings on the platform, and you can't mess it up too badly because if you miss one, the next one isn't far behind.