When should I replace kanji with hiragana?


When should I write 海山 and when should I write うみやま?




Well, it's _always_ safe to use the hiragana. You could technically write
Japanese entirely in kana, although it would become very difficult to read and
lack the context clues provided by kanji.

If `海山` is someone's (family) name, first make sure it is really pronounced as
`うみやま` because [it could have some other
pronunciation](https://japanese.stackexchange.com/a/5532/78). Secondly,
[depending on the context for which you're writing the
name](https://japanese.stackexchange.com/a/5316/78), you have several
different options.

If you're using `海山` to just mean "the sea and mountains" (or the phrase
`海山の恩`), you can, and probably should use kanji.

So what's the rationale for replacing kanji with hiragana? Well, if you don't
know how to write the kanji, you can always fall back to hiragana as I
mentioned. Another rationale would be writing something like a children's
book. Since young children may not know kanji, or how to read a certain kanji,
the author may use hiragana (although I believe `海` and `山` are likely taught
at a young age).

And although you didn't ask the inverse question, I'll answer it anyway.
What's the rationale for using kanji instead of all kana? As I said, ease of
reading. Once you start learning kanji, reading anything written in all kana
can be "difficult"; not that it's hard, but certainly can take longer. Kanji
also gives context. Japanese has **many** homonyms, so seeing something
written in kanji can give you a reasonable, if not exact understanding of what
it means. For example, if I write the word `いし`, you don't know if I mean
"rock" (`石`), "doctor" (`医師`), "will/volition" (`意志`), or any of the many
other words with that pronunciation.

