1 and "さよぅなら" are the most formal farewell expressions that anyone can use. "さよぅなら" is also used to bid farewell to primary and secondary school teachers.
2. Ordinary family and colleagues don't say goodbye with "さよぅなら".
Because in Japanese, it contains a meaning of never seeing each other again, or even farewell. Words that are not used at ordinary times have the feeling of where you are going and sadness, and contain the meaning of parting, so the scope of use is extremely narrow, so be careful.
Extended data
Other forms of saying goodbye in Japanese:
1, では ,また-Deva? ma ta
It means "goodbye" and "goodbye", in addition to "じゃまたじゃぁじゃじゃじじゃじゃぁ"
2. Rude (しつれぃ)します-si· Tureis Ma Su
It is a polite and solemn farewell language, used for people who are not close to each other or older than themselves. In addition, when you make a phone call, you usually hang up with "impolite", which means "I'll hang up first".
3. ぉききをつけて—o ki wo tu ke te
Used as a greeting when sending someone out or going out. However, acquaintances or peers often use "ぉ気をつけて", which means "Go all the way" and "Be careful on the road".
4. だぃじ) に-O Da Ejini
Generally used to visit patients or let patients take care of themselves. However, it can also be used to say goodbye to each other or at the end of a letter, meaning "good wishes" and "take care"
For example: "ooさん, ぉに" (oo, please take care. )
5. Nothing (ぶじじ)-Go Buggini
Used to say goodbye to people who are away from home.