いつの日か

someday

→ いつ
phrase Rare #35,826
someday A somewhat literary or formal way to say “someday” or “one day,” often referring to an unspecified time in the future.
JA: いつの日かイタリアに行きたいです。
EN: Someday, I want to visit Italy.

私はいつの日かアフリカに行きたい

I want to go to Africa someday.

いつの日か優しかったあなたの影がひとつ

One day, there will be nothing but the shadow of the kind person you once were.

— 別れる決心 (2022)

君の努力はいつの日か君のためになるでしょう

Your efforts will benefit you someday.