Ohayou gozaimas.= Good morning.
("ohayou" is from "hayai" early. "Ohayou gozaimasu"
is like "You are early.")
Konnichiwa.= Good afternoon./Hello. (Used in a daytime)
(Konnichi = today, "wa" is topic marker. "Konnichiwa"
is a short of something like "How are you TODAY?")
Kombanwa.= Good evening. ("n" becomes "m" before P, B, M)
(komban = this evening/tonight, "Kombanwa" is like "How
are you TONIGHT?")
Dewa, mata.= See you again. (dewa = well then, mata = again) Ja, mata.= See you again. (ja = casual of "dewa") Jaa(ne).= See you. (more casual)
Q: (O)genki desu ka.(o = polite) = How are you?
A: Arigatou gozaimasu. Genki desu.= Thank you. I'm fine.
("(O)genki desu ka" is not used often, because "Konnichi
wa" and "Kombanwa" include "How are you?")
Douzo.= Please. (Used when you offer something. ex. Here you are. Go ahead.)
Sumimasen.= I'm sorry. Excuse me. Pardon?
Chotto matte kudasai.= Just a moment, please.
(chotto = a little, mattekudasai = please wait)