Notes:
There is a rule for writing hiragana "wa (わ)" and "ha
(は)." When
"wa" is used as a particle, it is written in hiragana as "ha."
"Konnichiwa" or "Konbanwa" are now fixed greetings. However,
in the old days it was a part of sentence such as "Today is ~ (Konnichi wa
~)" or "Tonight is ~ (Konban wa ~)" and "wa" functioned
as a particle. That's why it is still written in hiragana as "ha."