Japanese Words

Hello = Konnichiwa
Good Morning = Ohayou / Ohayou-gozaimasu. (Polite)
Good afternoon = Konnichiwa
Good evening = Konbanwa
Good night = Oyasumi/ Oyasuminasai
Good bye = Sayounara
See you later = Dewa mata
See you tomorrow = Mata ashita
How do you do = Hajimemashite
I'm glad to see you = Oai-deki-te ureshii-desu
How are you? = Ogenki desu-ka
I'm fine = Genki-desu
And you? = Anata wa?
I'm fine, too = Watashi-mo genki-desu.
Thank you = Arigatou. /Arigatou-gozaimasu(polite)
Yes = Hai
Yes it is = Hai sou-desu
I got it/I understand = Wakari-masita
I know = Wakatte-imasu
I think so = Sou omoi-masu
Sure = Mochiron-desu
O.K. = Ii-desu/Ii-desu-yo
No = iie
I don't understand = Wakari-masen
I don't know = Shiri-masen
I didn't know that = Shiri-masen-deshita
I don't think so = Sou omoi-masen

Source : http://www2.tokai.or.jp