Well, if you are looking for an easy answer then, No, you do not need to learn Japanese to study in Japan. However, your options to choose courses and colleges can become very limited because not many institutions offer courses in English.
Do your research to find the right course and institution
As a foreigner with no or limited Japanese language skills, you might have to search for universities that offer courses you would like to pursue in English completely. It could be fashion tourism, animation, manga, design or other practical fields that you would like to pursue a course in, find a course that is completely in English to make the most of your learning.

Exchange programs
If you are not looking to study completely in Japan, you can still learn a lot through a student exchange program which is usually for a shorter span of time. Through these programs, you only spend a few weeks or months in Japan as a part of your learning process and may get away without learning the Japanese language.
Is learning the Japanese language helpful if you want to study in Japan?
It definitely is. Learning a local language always helps especially if you are planning to stay for a longer period of time.
For instance, if you are planning to enrol on an undergraduate course you may have to spend four years in Japan. Spending such a long time in a country without knowing the language restricts you in many ways.
If you are looking for a specialized study program, your options in English may be very limited.

The language barrier can be a big hindrance in a smooth everyday life in Japan
You may get along with English on campus, however, for your everyday needs outside the campus, learning Japanese can be helpful for the reason that most locals may not speak English. Otherwise, you might need help from a Japanese friend or depend on google translate for simple things like ordering food, finding your way or even getting help with some treatment at a hospital.
Socializing and making friends can also be difficult.
Without knowing the local language, you might restrict yourself to English speaking communities and miss out on making friends outside your comfort zone. This would also result in missing out on learning the Japanese culture from a Japanese perspective which is an essential element of learning in a foreign country.
Language can help you with a better travel experience during your stay
If you would like to explore the local tourist attractions or move away from the major cities, learning Japanese could always help. You may not always find signboards in English, thus learning some basic hiragana and kanji can be helpful.
