Do You Need to Learn Japanese Before Traveling To Japan
Straight to to the point, I would say no you do not, however, even learning some simple fraises can add exponential value to your trip. For background, I live and work in Japan and have 5 plus years of experience here studying as an exchange student and working in Comercial media, but when I arrived in Osaka for the first time I spoke a sum total of ZERO Japanese. From this experience I can answer this question in a definitive form: It was very doable to travel all around Japan without speaking the Language.
Arriving at the airport, there was an information desk visible under an " i " icon after exiting the terminal with an English speaking employee that can answer any questions about where you need to go and how you can best get there. All 3 international airports I have arrived at, Haneda, Narita, and KIX have all had this. In addition all train stations have english names on the map and english settings on the ticket kiosks. Google maps has been a great resource when searching for what trains and transfers can get you to your desired destination, and every station will have the station name in english visible at multiple locations. All of this plus the fact that most major stations will have station attendants (eki in 駅員) makes navigating the country without speaking Japanese a very achievable task. For all else, most major cities and more popular tourist destinations will often have many people around who speak English. Metropolitan areas often also have English instructions at stores and attractions and english menus at restaurants. On top of this, multiple times strangers have noticed me struggling with the language barrier and have offered to help using the english they know, or even if they are accustomed to quickly using a translation app. This kindness has been extended to me from strangers probably more than 8 times in the first 3 months here before I could speak the langue well enough to get around. I have also heard similar stories from other travelers including my 2 younger sisters and mother when they came to visit me, so I believe helpful bystanders are close to a constant here in Japan. Even so I know this can't be something one relies on when planning a trip, which leaves me to my second point.
Even learning some simple fraises can add exponential value to your trip. Instead of counting on someone to come and assist you if you are just looking confused (which I do swear happens here more than I ever would have guessed) Learning how to simply say excuse me to someone can initiate this. The word to politely say excuse me is: Sumimasen すみません
Just learning this can respectfully get someones attention at which time, if they seem they have a moment to spare, you can use a translation app, like google translate to ask them what ever you may need to know. In my first month here, being prompted to do this by my teacher I just spoke into google translate to have it spell out my question in Japanese, before showing my phone screen to the person I said excuse me to. This helped me out countless times and honestly it was such a morality boost seeing how friendly so many local people were while patiently helping me, a clueless foreigner, out with my journeys.
This being said, please don't be discouraged if you try this and you are ignored or turned down. Some people are just busy or may think that you are going to try to hit on them, so don't let it get to you I would like to say. This one fraise can add connivence to many elements of your trip, and learning just a bit more can add a great deal of immersion. I've made friends by simply complementing someones fashion or style in quite awful Japanese. Sono Kami ga mecha kakkoii その髪がめっちゃかっこいい
I was surprised at the friendships that could spring up regardless of language and cultural barriers. So anyway, it is extremely possible to travel here without speaking Japanese, however, if you can give it a shot just a bit, I believe it is very fulfilling addition. If you would like my tips on how I learnt Japanese here is a video I've made about the topic https://www.youtube.com/watch?v=OzyOjU-s660