Usage of kanji for words usually written in kana

From a small discussion on chat, I currently can think of three categories where the word is usually written in:

1. Hiragana but have kanji (成る, 有る, [炬燵]{こたつ}, etc)


2. Katakana but have kanji ([頁]{ページ}, [米]{メートル}, 亜米利加, 亜細亜, etc)


3. Katakana but have an alternate word that can be written with kanji (米国, etc)

I have a few questions about these:

• How commonly are these kanji used instead of their kana?


• In what situations are these kanji used instead of their kana?


• I've seen some of the #1 types used in some doujinshi with some written using the kanji and others written with the kana. Is there some kind of difference between writing some in kanji and others in kana such as if using some feels like old writing?


• I've seen some of the #2 types used on some websites, specifically 頁, such as this one (「106頁」) but then they don't use it again elsewhere (「ページ数」). Why is this?

Also, assume I'm talking about jouyou or otherwise relatively simple kanji.

Answer

I think possible reasons are:

1. Writer may be aiming for a particular kanji/kana balance.


2. Use of a kanji version over hiragana may supply a particular nuance or reduce ambiguity.


3. Use of the kanji form may reduce overall character count.


4. Use of the kanji may just indicate personal preference on the part of the writer (particularly in non-official works like doujinshi).

For something like ある you would have to be careful as there are different options with different nuances (在る for existence and 有る for possession). Using 成る for なる is not that uncommon when it is standing alone but should generally not be used if it's a case like できなくなる, only for the verb standing alone. There are cases like 居{い}る・要{い}る where you have completely different words (there's a joke I know that relies on this particular ambiguity), and so there may be occasions where the use of kanji makes the meaning clearer.

In some of the other examples, as pointed out on chat already, it's just a matter of brevity. 米国 and 頁 are shorter than the alternatives. Traditionally newspapers, and nowadays places like twitter, are very concerned about character count, so tend to use a kanji-heavy, condensed style. In fact you can use just 米 for "America/USA" (仏 for France, 露 for Russia etc). There is an alternative condensed way to write メートル in kana：　㍍　and I think 米 for "meter" is less common than 頁.

In addition, as kurosekai32 pointed out, 頁 is being used as a counter in your linked example, and I have a feeling (which I can't substantiate), that it's more likely to turn up as a counter than as a noun (e.g. in something like ページを開く).

Since 亜米利加 and 亜細亜 don't have the advantage of reducing the character count, they are not often used compared to something like 米国. (Although there is a 亜細亜大学 and other proper noun cases where using the katakana would be incorrect).

When people are writing for themselves and therefore not constrained by a style guide/publishers requirements (particularly given that computers make writing in kanji much easier), you will see an increase in the use of non-standard variants. It may be just author preference - I used to read a cooking blog where the author continuously used words like 胡麻{ごま} (sesame) and 胡椒{こしょう} (pepper), and I don't think there was a deeper reason for it than that she preferred the kanji versions. 炬燵{こたつ} will fall into this section.

There are particular examples like きれい・奇麗・綺麗 where the "official" version is often avoided. 奇麗 is the "joyo" version, where 奇 is used for sound, replacing 綺 but has a different meaning which doesn't really fit with the word - so some people will use きれい to avoid the use of 奇, and others will use 綺麗.