Japanese universities offer many courses taught in English. If you chose the course taught in English, Japanese language skill is not necessary for your study. However, if you learn Japanese language, it will open your mind and make your life more convenient and enjoyable.
Japanese Language Education in Your Country
Japanese Language e-Learning
Minato (Japan Foundation)
Both self-study and tutored course
from beginners to advanced learners
Japanese Language Proficiency Test (JLPT)