Non-japanese speaking travellers

What if we travel to Japan alone but we don't speak Japanese
I'm actually planning a trip with my best friend
two people

Then you'll join the other 20 million people a year that visit Japan that does not know the language.

If you can read English - then traveling around Japan I think is rather easy. Finding how to get to the correct station in Tokyo - that's not so easy. But I don't think speaking and reading Japanese is that much of advantage for this problem :-).....

Japanese people (such as station staffs and restaurant staffs) can understand some English perhaps more than what you are thinking (somewhat broken English and simple words only though mostly, but more than enough to guide and help you for directions, etc). You will have little problem on your trip in my opinion.

The difficulty depends on what parts of Japan youfll be visiting. Any place touristy like Tokyo and Kyoto and youfll be just fine. Those places are built for you. Rural expeditions could be trickier. But as stated above, even in the worse conditions, people manage to communicate in surprising ways.

It should be no problem. My mother who only speaks a German dialect, has never heard of google maps nor uses the internet nor a mobile phone , has travelled around Japan on her own for weeks, changing reservation for hotel rooms on the go, finding all her trains , living great experiences including in far flung destinations such as Hagi and returning one week later to my place at exactly the time she promised shefll be back.
On one of her last trips I suggested her a museum in Tokyo and told her the subway station name and museum name. When she arrived there she didnft immediately know where to go , so asked (remember she doesnft speak English) and a shop clerk accompanied her across the entire station to the entrance door of the museum.
On another occasion we were with her in a shopping mall and wanted to go to a Japanese Café. We were 2 at N2 Japanese level , 1 at N4 level and one fluent in English. Yet it was my mother who went to the information desk while we were still trying to make sense of a map of the mall, and got exact directions where the best Japanese cafeteria is.

So what I want to say, enjoying Japan does not depend on your English or Japanese capabilities but on your attitude.

No Japanese expects a foreigner to understand Japanese (which gets those actually speaking Japanese sometimes in strange situations) and most Japanese are aware that their English is poor or absent. But this doesnft stop them from helping you.

Enjoy your trip to Japan!