Would it be better to learn jappanese in japan or in the united states?

Question:

because i whant to major in jappanese launguges in a univirsity

Answer:

Learning in the native country of the language you are learning is always better due to the fact that you will be totally immersed. As children we learned our language through total immersion. Same method can applies to adults.

If funds are an issue, than learning it in the country you currently reside in might be the better choice.