ここだけの話だ

between you and me

→ ここ
phrase Rare #37,460
between you and me An idiomatic way to say that information is confidential or should not be shared with others. Often translated as “between you and me.”
JA: ここだけの話だが、この計画はうまくいかないと思う。
EN: Between you and me, I don't think this plan will work.

ここだけの話だが、彼はかなり愚か者だよ

Between you and me, he’s quite an idiot.

ここだけの話だ

This is just between you and me.

ここだけの話だこの品物は売れ行きが悪い

Between you and me, this item isn't selling well.

ここだけの話だけどあの太った醜い男は減量中なの

Just between you and me, that fat, ugly man is trying to lose weight.