I would like to make visitor visa.
and this time I wanna know about " letter" as a one of file for apply to embassy.

I thought that letter can make myself what is the aim to go america.

or

that letter suppose to ask my friend to write letter for me to visit there whom living USA?
Anonymousthat letter suppose to ask my friend to write letter for me to visit there whom living USA?
This is probably what is meant, but you should contact the US embassy in Tokyo to confirm what they require.

If you want to visit the U.S., you need to obtain a visa first. Before you apply, you have to decide what the purpose of your trip is. For instance, if you want to temporarily in the USA, then you need a non-immigrant visa, like B-2. Although, in case you want to work and live in America for a while, apply for the immigrant visa. As for the B-2 tourist visa, it's a non-immigrant kind of visa for people who travel to the U.S. for treatment or personal pleasure. It doesn't allow to work live within the United States.