ので in これが僕ので、それが君のだ。

What does ので in これが僕ので、それが君のだ mean exactly?
(Translation: This is mine, and that’s yours.)

I think in this case the 「で」 is the 〜て form of 「だ」.

The 〜て form is used to join two sentences happening at the same time in this case.

@Nearos

The Japanese sentence should be rewritten as:

これが僕ので、それが君のだ。or

こっちが僕ので、そっちが君のだ。(this sentence sounds better because the pronouns are casual.)

I guess the original author wanted to use a phrase ので and they forgot to remove “ので in”.

Here is the grammatical breakdown.

  • これが僕のものだ。そして、それが君のものだ。(This is my possession. And, that is your possession.)
  • これが僕のだ。そして、それが君のだ。(This is mine. And, that is yours.)
  • これが僕ので、それが君のだ。(This is mine and that is yours.)