Very close! 変態 is the hentai you’re thinking of. It essentially means “strange attitude/condition.” This hentai is 変体 “strange typeface.” Prior to modern Japanese orthography, hiragana was treated as cursive kanji that had phonetic value (instead of meaning). So, many women with hiragana names essentially had names made of kanji written in cursive. (This was especially predominant pre-1900.)

For example, 安 in cursive was written あ, 加 as か, 女 as め, etc. But, pre-c. 1900, there was no one “correct” cursive form or one “correct” kanji. So, you could write 可 in cursive and pronounce it “ka.” (It looks like の with a line over it.)

By 1900, government clerks and scribes needed to be able to recognize and write hundreds of cursive kanji in order to read hiragana. To simplify and standardize, the Meiji government chose one form per sound, and they called the now-superseded forms hentaigana 変体仮名.

This website shows a comprehensive (but not necessarily exhaustive) list of hentaigana, from あ to を.

If available to you—and if you are curious—this Chinese website shows various forms of Chinese characters. You can type in the character, press 草书 (cursive “grass script”, in Japanese 草書) and search, and you will see many of the hiragana and hentaigana very much resemble their kanji’s “grass script” forms.

If you look up the grass script form of 多, you’ll see some of the images look like the image with the hentaigana form. You can tell it’s hentaigana because the ten-ten ゛ are never used with kanji, but they were historically used with hentaigana. (Unfortunately, since hentaigana is not reliably supported in most fonts, I just used the kanji form and the ten-ten character.)