ugly duckling

US /ˈʌɡ.li ˈdʌk.lɪŋ/
UK /ˈʌɡ.li ˈdʌk.lɪŋ/
"ugly duckling" picture
1.

みにくいアヒルの子

a person or thing that is initially unattractive or unpromising but eventually becomes beautiful or successful

:
She was an ugly duckling in high school, but she grew up to be a stunning model.
彼女は高校時代はみにくいアヒルの子だったが、成長して見事なモデルになった。
The old building was considered an ugly duckling, but after renovation, it became the most beautiful one in the city.
その古い建物はみにくいアヒルの子と見なされていたが、改築後、市内で最も美しい建物になった。