Hi! I’m reading through the manga Happiness by Oshimi Shuzo and am having trouble understanding why the「んだ」construct is being used in seeking out an explanation or inquiry.
In this context, the main character has just recovered from being assaulted in the middle of the night, and is talking to his brother, who says:
> 兄貴：「けどさあ… ムカつくよな…」
> 主人公：「え？」
> 兄貴：「おまえを襲ったやつ、**なに考えてんだよ**…マジでゆるせね」
I’ve been going off of [Tofugu](https://www.tofugu.com/japanese-grammar/explanatory-nda-ndesu-noda-nodesu/) and Tae Kim to understand the construct better but can’t seem to find a good explanation for its usage here. Would anyone be able to help? Unless this particular usage is valid and just isn’t commonly used.
5 comments
that’s not just the explanation んだ form, it’s a contraction of 考えているんだ
考えてる is also a contraction of 考えている but this is one syllable even shorter, plus んだ, when someone is really slurring their words and talking fast
think “wutthfhethinkinbout” instead of “what the fuck is he thinking about”, that’s the flavor it gives me
In the Tofugu link, is the section “の AND んですか FOR SEEKING EXPLANATION” not what you are looking for?
Anyway, the short answer is that のだ•んだ can also be used to request for explanations.
>精選版 日本国語大辞典
>③ (疑問詞を受けて) 意図や事実をたずねる気持を表わす。
>※滑稽本・七偏人（1857‐63）三「何故横目で人を見るんだ」
③ To express a feeling of asking about intentions or the truth (when used with an interrogative).
I’m not 100% but it’s just a language quirk that would allow someone to distinguish rhetorical from actual questions it’s something English doesn’t have.
If I asked someone “what were you thinking?” as a chastising measure 99% of the time I’m not asking literally. There’s nothing that gives me away aside for intonation.
If you feel like watching a YouTube video I’d recommend [Kaname’s](https://youtu.be/SblaSl7ZVY0) video on this topic.
んだ provides explanation based on some sort of context.
When you walk into my house and see a heap of tomatoes, you’re thinking “what’s with the tomatoes?!” トマトが多いね。どうしてトマトがあるの？
My explanation will also come from context, whether or not you’ve vocalized the question: 畑があって、毎年近所の人に配るんだ。 “I have a garden, and I give them (the tomatoes) out to my neighbors every year. That’s why I have so many.