Reading "プラチナデータ" by 東野圭吾.

Not clear on the meaning of:

"俺、何度も彼女を殺しそうになったもんな" -

"I often almost killed her ... (monna?)"

What is "monna"? I suppose "mono nara" ("if that thing"), but then I don't understand the whole sentence - is it "If I often almost killed her"?

4 Answers 4


More than anything, it is a colloquial way of adding the nuance of "retrospective confession or boasting" in my own words.


I think that it comes from the grammar form ~もの + だ. Which when changed to casual becomes もんだ which then you could add a な to.

ものです-> もんだ->もんだな->もんな

I think this may be a usage of 'reason/explanation' version of ~もの, perhaps in a sentence before or after the character is talking about why he had often almost killed her?

  • 1
    nope, the 丁寧語 of なったもんな is なりましたもんな, not なったものですな. This is a sentence ending particle, not a formal noun.
    – dainichi
    Commented Oct 23, 2013 at 7:48
  • I'm not really sure what your comment is in reference to, but what I'm trying to explain is that the もんな from the poster's question comes from もの and な. I edited the question so hopefully that is more clear
    – ishikun
    Commented Oct 23, 2013 at 8:31
  • 1
    It's correct that it comes from もの+な, but ものです is not relevant.
    – dainichi
    Commented Oct 23, 2013 at 9:41
  • I apologize if it was confusing, I was only using the words 'ものです' as a reference to that grammar structure as explained in the link. I've changed it to もの+だ to make it even clearer.
    – ishikun
    Commented Oct 23, 2013 at 9:53
  • 3
    @ishikun Let me try and see if I can get it right: a formal noun (形式名詞) is like a noun in form, so it can turn the clause before it into a relative clause and be followed by だ. (As a formal noun, もの is a nominalizer.) But since this is the sentence final particle (終助詞), it doesn't act like a noun, and you can't put だ after it any more than you can put だ after よね. (Plus, it can come after だ, something no noun can do.)
    – user1478
    Commented Oct 23, 2013 at 11:42

It's a variation of entry 2イ here:


As Goo says, it's basically an exclamatory way to state a reason for something, 「詠嘆の意をこめて理由を表す」. I don't have the context in this case, but I would say that in most cases the meaning is approximately the same as


and I would give the English translation as roughly

I did almost kill her several times, didn't I...

  • Thanks for the replies! This sentence is uttered by a character being interrogated by the police, boasting about his "prowesses" with his 彼女 using a special device called a "電トリ ". I would probably go with "もんな" -> "からな", since the character is not offering any reason other than boasting he is really proud of himself...
    – Swalbol
    Commented Oct 24, 2013 at 7:19

It is similar to "right ?" Used by men The equivalent used by women would be もんね

相手に自分の言ったことへの同意や、肯定を求める言い方です。 男性の言い方です。 女性であれば「〜もんね 」です。


今日って寒いもんな。 It's cold today, right ?

Source: https://hinative.com/ja/questions/1911840

  • 相手に自分の言ったことへの同意や、肯定を求める言い方です。 男性の言い方です。 女性であれば「〜もんね 」です。 今日って寒いもんな。 <- When you copy from another page, please always include the source, and clearly show which part of your answer is citation and which is your original.
    – chocolate
    Commented Dec 29, 2020 at 16:22
  • Hi, you are right, I have thus updated the answer
    – Makoto
    Commented Dec 29, 2020 at 16:23

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