HelloHello is commonly translated to Konnichiwa (Kon-ee-chee-wa).
This is basically correct. Although in Japan greetings are more strongly based on the time of day than say English. In the morning on meeting someone you know – a Japanese person is highly unlikely to say “konnicihwa”. Instead they will say the equivalent of good morning.
Hello said in the morning (like “good morning) is Ohaiyou Gozaimasu (O-hi-yo Go-za-eye-mass).
Hello said around noon is good old, Konnichiwa.
Hello said after noon (like “good afternoon”) is Konbanwa (Kon-ban-wa).
That’s pretty much all the greetings you’ll need. If you’re answering the phone, rather, than saying one of the above you say “Moshi, Moshi” (mosh-ee, mosh-ee).
It you haven’t seen each other in a long time then something a little like, “long time no see” is commonly said – Sashiburi (sa-she-bu-ree)
GoodbyeI’m sure most people are familiar with goodbye it’s Sayonara (Sa-yo-na-ra).
If you’re a close friend the casual way of saying goodbye is Ja-ne (like jar-neigh!)
Japanese people will also say “bai – bai” can you imagine how this is pronounced? (Pro-tip: Bye bye)
If it’s very late then you will be more likely to say “Good Night” this is “Oyasuminasai” (Oi!-ya-sue-me-naa-sa-eye).
You are now are an expert greeter and can have that job as a door man that you’ve always secretly longed for.
Edit: There have been a few comments about さよなら having a う as in さようなら。Both spellings are used see (http://language.tiu.ac.jp/materials/jpn/yomi/yomi02.html). In this page I've tried to give the a spelling so that some coming from English would be more likely to pronounce it recognisably.
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