It is an advantage to learn some Japanese. Maps at the airport in fact were prepared in different languages, which include English. The Katakana for Tokyo Tower was similar to English pronunciation… in spoken language, local people should understand foreigners’ talks like ours.

Truthfully most things are also written in english, including all the trains and subways.
Don’t bother learning Hiragana if you don’t speak much japanese cause even if you read it you won’t be able to understand it.
It might be worth learning Katakana though since Katakana words often sound like their english equivalent.

No, you don’t “need” to learn any… but it’s polite and helpful to learn greetings and other chit chat.