Hi, there are several good-bye expressions in Japanese, the choice among which depends on the degree of separation.
① さようなら [sayo-nara] ⇒ Good-bye
「さようなら[sayo-nara]」indicates that the speaker does not expect to see the person spoken to before he “turns a page in his life”; not until a new day arrives, or until fate brings the two together again. It sounds dramatic and ritualistic, and its daily use is largely restricted to school children taking leave of thier teachers.
And generally we use ② , when we expect to see each other again fairly soon.
②
またね [matane] ⇒ See you
じゃあ、また [ja- mata] ⇒ See you
また、あした [mata ashita] ⇒ See you tomorrow
[These are casual expressions. You can use them between friends.]
Be sure to try it♡