Japanese Grammar: Master the Explanatory “~んです” (n desu)

Japanese Grammar: Master the Explanatory “~んです” (n desu)
Meaning & Usage

✨ Basic Meaning

The grammar point ‘んです’ (n desu) is used to provide an explanation, seek clarification, or emphasize the reason behind a situation.

🎯 Primary Function

Explanatory Emphasis / Contextualization.

📋 Grammar Structure

Plain Form + んです
Plain Form + んです
Plain Form (~だ → ~な) + んです
Negative Plain Form + んです / ~じゃないんです

🎭 Usage Contexts

🏢 Formal Situations

Used in polite conversation with colleagues or superiors when explaining reasons. In very stiff formal writing, ‘のです’ is preferred.

😊 Informal Situations

In casual speech, ‘んです’ changes to ‘んだ’ (n da) or just ‘の’ (no) depending on the gender and regional dialect.

✍️ Written Language

Rare in formal reports, but common in emails, blogs, and fiction dialogue. ‘のです’ is used for formal essays.

🗣️ Spoken Language

Essential for sounding natural; used to link the current situation to a reason.

💡 Common Applications

Asking for explanation
Used when you see a situation and want to know the underlying cause or reason.
Example: どうしたんですか。 (What’s wrong?)
Giving a reason
Used to explain the ‘why’ behind an action or state, often answering a ‘why’ question implicitly or explicitly.
Example: 時間がなかったんです。 (I didn’t have time.)
Softening a request or refusal
It adds a ‘contextual cushion,’ making a refusal or request sound less abrupt by providing a background reason.
Example: 用事があるんです。 (The thing is, I have some errands to run.)
📊
Frequency
Extremely high in daily conversation.
🎚️
Difficulty
N5 / N4
Example Sentences
Example #1
どうしたんですか。
Furigana: どうしたんですか。
Romaji: Doushita n desu ka.
English: What happened? (Why do you look like that?)
Example #2
頭が痛いんです。
Furigana: あたま(頭)がいたい(痛い)んです。
Romaji: Atama ga itai n desu.
English: I have a headache (and that is why I am acting this way).
Example #3
どこでそのカメラを買ったんですか。
Furigana: どこでそのカメラをかった(買った)んですか。
Romaji: Doko de sono kamera o katta n desu ka.
English: Where did you buy that camera?
Example #4
病院へ行きたいんですが、道を教えていただけませんか。
Furigana: びょういん(病院)へい(行)きたいんですが、みち(道)をおし(教)えていただけませんか。
Romaji: Byouin e ikitai n desu ga, michi o oshiete itadakemasen ka.
English: I want to go to the hospital, so could you please show me the way?
Example #5
今、ちょっと忙しいんです。
Furigana: いま(今)、ちょっといそが(忙)しいんです。
Romaji: Ima, chotto isogashii n desu.
English: I’m a little busy right now (explaining why I can’t help).
Example #6
実は、寿司があまり好きじゃないんです。
Furigana: じつ(実)は、すしがあまりす(好)きじゃないんです。
Romaji: Jitsu wa, sushi ga amari suki janai n desu.
English: The truth is, I don’t really like sushi.
Example #7
バスが来なかったんです。
Furigana: バスがこ(来)なかったんです。
Romaji: Basu ga konakata n desu.
English: I’m late because the bus didn’t come.
Example #8
どうして何も食べなかったんですか.
Furigana: どうしてなにも(何も)た(食べ)なかったんですか。
Romaji: Doushite nani mo tabenakatta n desu ka.
English: Why didn’t you eat anything?
Example #9
もうお腹がいっぱいだったんです。
Furigana: もうおなかがいっぱいだったんです。
Romaji: Mou onaka ga ippai datta n desu.
English: Because I was already full.
Example #10
傘を探しているんです。
Furigana: かさ(傘)をさが(探)しているんです。
Romaji: Kasa o sagashite iru n desu.
English: I’m looking for my umbrella. Have you seen it?
Notes & Nuances

📌 Important Points

Visual Cues
When using ‘ndesu’ in a question, it implies you’ve seen something (like someone carrying luggage) and are asking based on that visual evidence.
Example: どこへ行くんですか。
Introductory Use
Often used at the start of a sentence to introduce a topic before making a request.
Example: ~んですが、…

⚠️ Common Mistakes

❌ 休みんです (Yasumi n desu)
✅ 休みなんです (Yasumi na n desu)
Nouns and Na-adjectives require ‘na’ before ‘ndesu’ in the present affirmative form.
❌ 私は田中なんです (Watashi wa Tanaka n desu)
✅ 私は田中です (Watashi wa Tanaka desu)
Don’t use ‘ndesu’ for simple factual self-introductions without context. It sounds like you are explaining why your name is Tanaka.

🏛️ Cultural Context

Politeness Level: It is polite (Desu/Masu level). It shows consideration for the listener by providing context.
Social Situations: Crucial for social harmony (wa) as it explains actions rather than just stating them bluntly.
Regional Variations: In Kansai dialect, it often becomes ‘ねん’ (nen).

🔍 Subtle Differences

~です vs ~んです
‘Desu’ is a plain statement of fact; ‘ndesu’ provides an explanation or asks for one.
When to use: Use ‘desu’ for objective facts; use ‘ndesu’ when there is a context or a ‘why’ involved.

📝 Conjugation Notes

For Nouns and Na-adjectives in the non-past affirmative, you must add ‘na’ (e.g., 好きなんです, 病気なんです). For all other forms (past, negative, I-adjectives, verbs), simply use the plain form before ‘ndesu’.

🔊 Pronunciation Tips

The ‘n’ is a nasal sound. Ensure the ‘n’ is clearly voiced but short before the ‘desu’.

🧠 Memory Tips

Think of ‘ndesu’ as the ‘The thing is…’ or ‘It’s because…’ of Japanese. It ‘wraps’ your sentence in a layer of explanation.

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