ので — Reason / Cause (soft, polite)
Connects a reason to a result, like から (because), but softer and more polite. It presents the cause as an objective, natural consequence rather than a personal excuse.
Structure
[Reason clause] + ので + [Result]
Examples
電車が遅れたので、遅刻しました。
Densha ga okureta node, chikoku shimashita.
Because the train was delayed, I was late.
電車が遅れた (the train was delayed, objective fact) + ので + 遅刻しました (I was late).
暑いので、窓を開けてください。
Atsui node, mado o akete kudasai.
It's hot, so please open the window.
暑い (plain form) + ので — presents the heat as an objective reason for the request.
明日はテストがあるので、たくさん勉強します。
Ashita wa tesuto ga aru node, takusan benkyou shimasu.
I have a test tomorrow, so I'll study a lot.
テストがある (there is a test) + ので + 勉強します — the reason flows naturally into the result.
• な bridge: ので comes from の + で, so nouns and な-adjectives take な before it: 静かなので (because it's quiet), 日曜日なので (because it's Sunday). Never 日曜日ので. • Because it sounds objective and soft, ので is preferred in polite requests and explanations.
Commonly confused with
The JLPT rarely asks whether you recognise a pattern — it asks which of several similar patterns fits. These are the ones ので is tested against.
vs から
から states a reason more directly/subjectively and is common in casual speech and firm assertions; ので is softer and more polite, framing the cause as natural fact.
vs のに
のに means 'even though / despite' (contrary result), whereas ので means 'because' (expected result) — do not confuse them.
More conjunctions
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