I lived in Japan for a year and I was sent to work there. To tell you realistically, I can guess your work content and advise you to do what you can. Think it over. Japan is not a place to find gold. Let me stay there and I'll come back. If you are still sure you want to go, you can contact me and I will help you, because everyone is from China.
The following is what you asked for translation:
わたくしはとします. Yan Jianv ですが, 19 です. I'm going back to Japan. Don't be a relative at home.
What level of school do you want to go to? Generally, a better university requires Japanese level 1, which is very difficult. Of course, there are also those that only require level 2. You can go to preparatory school, which is better than language school. After that, you can go directly to college, and it should be easier to go to a better school. Without the basic knowledge of Japanese, it is impossible not to spend three or five years. If it really doesn't work, let your girlfriend accompany you and go to Japan with you.