How can 蛙 be read as あ ("a") in Asui Tsuyu's name?


In Japanese, Asui Tsuyu's name is written as 蛙吹 梅雨. Most of the kanji in her
name makes sense. 梅雨 is read as つゆ ("tsuyu"), and 吹 is read as すい ("sui"), but
from what I know 蛙 is read primarily as かえる ("kaeru"), and can also be read as
かわず ("kawazu") or かいる ("kairu"), but I can't find anything about reading it as
"a". Moreover, it isn't a jōyō kanji or a jinmeiyō kanji, so I find it
unlikely that it's something that happens when the kanji is used in names, as
it generally shouldn't be used in names at all. So what's the deal?




**[蛙](https://jisho.org/search/%E8%9B%99%20%23kanji) has ア【a】 as one of the
_on-yomi_** , and kanji compound is usually read in _on-yomi_ (some also have
a reading in _kun-yomi_ , but in general, all of the kanji in the kanji
compound are read in either _kun-yomi_ only or _on-yomi_ only, but not mixed).

Some example where [蛙 is read as
"a"](https://jisho.org/search/%E8%9B%99%20%E3%81%82):

>   * 蛙黽 ( ** _a** bou_): tree frog (toad)
>   * 蛙鳴 ( ** _a** mei_): frog calling​
>   * 蛙鳴蝉噪 ( ** _a** meisensou_): annoying noise; fruitless argument; useless
> controversy
>

As for Asui, her kanji representation 蛙吹 is read in _on-yomi_ as 蛙（ア） and
[吹（スイ）](https://jisho.org/search/%E5%90%B9%20%23kanji)




**[蛙](https://jisho.org/search/%E8%9B%99%20%23kanji) has ア【a】 as one of the
_on-yomi_** , and kanji compound is usually read in _on-yomi_ (some also have
a reading in _kun-yomi_ , but in general, all of the kanji in the kanji
compound are read in either _kun-yomi_ only or _on-yomi_ only, but not mixed).

Some example where [蛙 is read as
"a"](https://jisho.org/search/%E8%9B%99%20%E3%81%82):

>   * 蛙黽 ( ** _a** bou_): tree frog (toad)
>   * 蛙鳴 ( ** _a** mei_): frog calling​
>   * 蛙鳴蝉噪 ( ** _a** meisensou_): annoying noise; fruitless argument; useless
> controversy
>

As for Asui, her kanji representation 蛙吹 is read in _on-yomi_ as 蛙（ア） and
[吹（スイ）](https://jisho.org/search/%E5%90%B9%20%23kanji)

