「したく」in「いたずらがしたくなった」


The full sentence is 「いたずらがしたくなったのです」

Is したく the く-form of したい + なる in which case the sentence would mean "he grew
wanting to play some frolics"?

Or is したく the hiragana of 支度 in which case the sentence would mean "Some
pranks were prepared"?




This is probably just したく+なる (your first guess). Addressing [your
comment](https://japanese.stackexchange.com/questions/97017/%E3%81%97%E3%81%9F%E3%81%8F-in-%E3%81%84%E3%81%9F%E3%81%9A%E3%82%89%E3%81%8C%E3%81%97%E3%81%9F%E3%81%8F%E3%81%AA%E3%81%A3%E3%81%9F/97018#comment157953_97017)
in the question,

> ok but if it was したい, shouldn't the sentence be 「いたずらをしたくなった」？

when using the たい construction, both particles を and が can be used. See
[this](https://japanese.stackexchange.com/questions/15171/%E3%81%8C-vs-%E3%82%92-in-
sentences-of-desire-%E3%81%9F%E3%81%84) and
[this](https://japanese.stackexchange.com/a/68265/32952) Q&A entries to know
more about the different nuance for each case. According to [this
article](https://www.wasabi-jpn.com/japanese-grammar/how-to-express-desire/),
at the section "Advanced Topic: を (Direct Object) VS. が (Object of Emotion)":

> [For the construction Vたい] when the particle を points out direct objects,
> you can replace it with the particle が. The meanings are the same, but there
> are some cases where you need to use a particular particle. Be careful; if
> the particle を has a different function, the replacement doesn’t work. For
> example, with this sentence: 公園{こうえん}を歩{ある}きたいです (I want to walk at the
> park), the を points out locations to pass.

> 漢字を勉強したい（です）。 [I] want to study kanji.

> 漢字が勉強したい（です）。 [I] want to study kanji.

