こんにちわ Or こんにちは
I have a hiragana question...
This is how I thought hello would be written: こんにちわ
But I have found this also listed as a correct version: こんにちは
Why is the second one correct when the last character is HA は ? (The second one appears to be the preferred written version.)
In my dictionaries, both versions are listed as “hello”.
My Japanese friend says that こんにちは is correct when you write it but pronounce it as こんにちわ. She was not able to tell me why.
As others have mentioned, こんにちは is a shortform of a full phrase used as a greeting, with the は actually not being part of the word, but the topic particle "wa". So literally it's saying "On the topic of today..."
は is pronounced "ha" when it is part of a word, but "wa" as a topic marker.
It was originally pronounced "pa" then changed to "wa" at the end of words which is how it sounded as a topic marker; but during the language reform many kana's pronunciations were changed and rearranged and standardized.
Since most words are written in kanji, changing the kana wasn't a huge deal since the only thing that really needed to be adjusted were the pronunciation guides for the kanji. But since kana like は (wa) へ (e) を (o) were so commonly used as particles, rather than completely reteach a population how to read and write, and change all of the existing written texts, they chose to instead to simply keep the original readings to make it easier as well as adopt their new current readings (ha, he, wo)
You can find answers to a lot of common questions on Google, this is from Quora:
"It's because the modern "こんにちは" is a shortened version of the old greeting style. It helps to know that the kanji for konnichi-wa is 今日は (today). A long time ago people used to greet each other by saying things like " 今日はいい天気ですね" (The weather is nice today), or "こんにちは暑い" (Today is hot). "
As far as I know this is just a quirk of Japanese. There are only a few other situations where は is pronounced as wa, usually in greetings. If I remember correctly は used to always be pronounced as wa, but then became ha, same with を, which used to be wo, but is now just o.