Many international students think that they need to go to a Japanese language school in Japan and get certain level of JLPT (Japanese-Language Proficiency Test) or EJU (Examination for Japanese University Admission for International Students) to enter a university in Japan. This is true and not true. It depends on the department you will choose. For example, if you would like to enter the department of Japanese literature, many universities would require you to have Japanese skills to pass the entrance examination.
However, there are many universities which have a department, offering English based degree programs and accept international students who do not have Japanese skills. Such kind of departments can be the department of Global Business, the department of International Studies, and so on. So, if you are interested in studying that kind of academic fields and choose the department which does not require Japanese skills for entrance examinations, you can save a lot of time and money that would cost to get Japanese skills before you enter a university.