After being in Japan for about 5 months and visited some of the places around tokyo, if you ask me this question, then I would say 10 times YES!!
Do you need to be professional in Japanese?It depends on your purpose of speaking Japanese.
1.
Just for traveling or site seeing in Japan - You need to know basic Japanese language. I think
JLPT Level 4 (JLPT - Japanese Language Proficiency) would be more than sufficient! Or you can buy a book called "
Japanese for busy people" to know some basic Japanese. This book is really nice one, as you need not learn the complex Japanese script to read it.
In main Tokyo city at least I would say that you may find someone who can speak English and will help you. But in suburbs of Tokyo, or the cities in Tokyo state as it is known in Japan, you will hardly find a person speaking English! On railway stations you will find the railway persons who can speak English. But no taxi driver or bus driver can speak English in suburbs...at least I haven't met one!
2.
Working with Japanese company in Japan- Here you need to be know Advanced Beginner level japanese i.e. equivalent to
JLPT Level 3. Rather I would say if you know more than JLPT Level 3 it would be better. As Japanese people don't recognize the difference between these levels, I mean they are not bothered of what level you have learned. They can speak any format of sentence and you may misinterpret the meaning you are not professional in Japanese!!
Everyday you will find new words and you will realize that you know nothing about Japanese language. But don't feel discouraged about it as you can very well manage it if you are SAN Q or JLPT Level 3.
3.
Day to day survival - If you are not working with Japanese company and only want to know japanese for day to day activities like shopping in japanese store, then also I would recommend the same book "
Japanese for busy people". (No! I don't get any commission for recommending this book! its by my own experience, I am advising you!).
Easy (and cheap as well) way of learning Japanese when in Japan is to learn at local City Hall. Japanese volunteers can teach you Japanese language at per hour basis. This may be free or have some nominal charges. Here are some links -
Tachikawa, TokyoHachioji, TokyoConclusionKnowing average Japanese would be sufficient! Japanese is quite fun and I would say it is easy to speak language (reading is bit difficult, but fun as well)! If you know Hindi, then its easy for you to learn Japanese, as grammar in Japanese is quite similar to Hindi. For a English person learning Japanese could be slightly difficult, as the grammar in Japanese is quite different than English. But if you are determined to learn it, no one can stop you from being 上手 【じょうず- expert】 in Japanese! Wish you best of luck!
