please tell me the truth?

Well, I think most people in the USA will try make overcoming the lack of expertise in the English language as painless as possible. Of course, there are always those people who have prejudices against a particular group of people. So, if your question is whether people will be unfriendly with you because you don't speak English well, then the answer is no. There may be a sort of discomfort for the person who does not speak English well, but generally I think most people in the USA will be sympathetic to someone in the USA who doesn't speak English. There may be some bias toward Spanish speakers because there have been so many Spanish speakers who come here, never learn English, and have no respect for our language, our customs, or our laws.

If your path crossed my path, I would be friendly, polite and respectful to you. 

I am a polyglot, and foreign people are interesting to me. 

Many Americans are frustrated with their lives and act rude as a defense mechanism to outsiders. 

The whole, large United States of America 🇺🇸 speaks English.  No other language is necessary, but many foreign languages exist in various areas. 

California is probably the best place to be able to speak Japanese only.  Japanese is not a popular language outside of California.  Even poor English is useful.

I think most people would be very kind and understanding.Of course very rude and nasty people you will find all over the world.

User -- There IS the type . . . it's ONE type.

In the U.S.

"there are all types".

There are the type of people

who are fascinated with foreign languages and people

and (so) who love to converse with and befriend such people.

There are the type of people

who think that anyone who speaks with a foreign accent

is somehow wrong or disrespectful or stupid.

And...lots of people somewhere in between those two extremes.

You won't be treated respectfully by everyone.

You won't be treated disrespectfully by everyone.

Hopefully, there are far fewer who show disrespect than there are who show respect.

Happy spring   

The truth is that it entirely depends on WHERE in the US you travel. In sophisticated, cosmopolitan areas of the country your ethnicity, nationality and accent will barely be noticed. In more rural, less sophisticated and more socio-economically disadvantaged areas, it's possible that you will notice a bit of xenophobia (fear of strangers). There are a large number of Japanese tourists that regularly visit this country however, and your experience will most likely be entirely positive. 

It depends on who you speak with. Professional people will not feel bad trying to communicate with you. Average people might be annoyed. But don't let that deter you. Americans think highly of the Japanese people.