As alluded to earlier, please tell us what you want to study in Japan. Some majors can get by with English only, but that's just a bare handful of universities here. I work at a uni,, and undergrads from foreign countries are fewer than 5 out of 1000 students. They all have pretty high Japanese skills.
If you intend to study at a university that doesn't cater to English, you have to realize that lectures and textbooks and Powerpoint presentations and conversations with the teacher/students and any handouts or web sites will undoubtedly all be in Japanese. So, it's not like you can just begin studying and hope to get by knowing how to say good morning, thank you, and where is the toilet?
I'm not going to look up your other posts. When you write here that you want to study in Japan "soon", how soon is that? If it's an unrealistic time frame, I think you should be able to determine what to do.
Last question. Why Japan?