Explanation & Emphasis: 〜んです / 〜のです
The grammar ~n desu / ~no desu is incredibly common in spoken Japanese, but hard to translate directly. It signals that you are providing an EXPLANATION or seeking one.
What does ~n desu mean?
Think of ~n desu as adding the nuance: 'The fact is that...' or 'The reason is that...' or simply 'You see,...'. It signals to the listener that what follows is relevant context or an explanation.
GIVING an explanation: 'Sushi o tabemasen.' (I don't eat sushi) is a plain fact. 'Sushi o taberarenain desu.' (The fact is I can't eat sushi) — implies there's a reason, like an allergy.
SEEKING an explanation: 'Dou shitan desu ka?' means 'What happened / What's the matter?' (Asking for an explanation of an unusual situation).
How to form ~n desu
Example Sentences
Teacher's Advice
~n desu makes everything sound like you are explaining yourself, which can feel like over-justifying in some contexts. For simple factual statements with no implied explanation, just use the plain masu/desu form. Use ~n desu when there is an emotional or contextual reason behind what you are saying.
There is one situation where omitting ~n desu sounds wrong: responding to something the other person can see. If a friend sees your suitcase and asks about it, 旅行に行きます sounds robotic — the natural answer is 旅行に行くんです ('the thing is, I'm going on a trip'). Whenever your sentence explains a visible situation, reach for ~n desu.
JLPT Exam Patterns
- •Na-adjectives and nouns use 'na' before n desu: 元気『な』んです (N4)
- •Using ~n desu ka to ask for an explanation in conversation (N4)
- •~n da is the casual equivalent for dialogue questions in the N4 reading section
- •実は〜んです as a set phrase for introducing news in listening dialogues (N4)
- •Choosing between plain です and 〜んです based on whether the context implies a reason (N4)
Related Grammar
Sound More Natural
Practice adding ~n desu to sentences to make explanations feel natural.