別の話だ

that's another matter

→ 別
phrase Rare #30,267
that's another matter Used to say that something is a separate issue or a different matter.
JA: それは別の話だ。
EN: That's another matter.

別の話だけど別に気にしてない。

That’s a separate matter, but I don’t really care.

店長はそれとは別の話だ

The store manager is a separate matter.

— レザボア・ドッグス (1992)

これは別の話だ

That's a different matter.

— ブゴニア (2025)

それとこれは別の話だ。

That's a separate matter.

全く別の話だ

That's a completely different matter.

— 嵐の中で (2018)