I want to travel to Japan next summer vacation. How to learn Japanese to reach the level of basic communication?

0 foundation, it is best not to try to learn. If you speak English directly, the other party will know that you are a foreigner. If you know English, the other person may speak English. If you don't know, make a gesture or something. Once you speak Japanese, people may answer you in Japanese. At this time, people with poor foundation will be confused and counterproductive. Of course, if you are interested in learning, you can, but if you are not confident that you can understand what others say, you'd better not say it.