うん
うん
un
= yes; yeah; uh-huh; okay (informal)
うん is the most casual way to say yes in Japanese — a relaxed, spoken-only contraction of はい (hai) that you’ll hear constantly among friends and family, but never in a meeting room or classroom. It sits at the very bottom of Japanese’s formal agreement scale, which makes knowing exactly when to use it just as important as knowing what it means.
うん functions as an informal affirmative, equivalent to English “yeah,” “yep,” or “uh-huh.” Japanese has a layered system of agreement words, each carrying a different register:
• うん — the most casual; used only with close friends, family, or peers of equal or lower status
• ええ — slightly softer than はい, associated with female speech or gentle agreement in relaxed conversation
• はい — the standard polite yes; appropriate for teachers, colleagues, strangers, and any formal setting
• そう / そうです — “that’s right”; used to confirm a statement rather than answer a yes/no question
Beyond simple agreement, うん also serves as an 相槌 (aizuchi) — a back-channel signal that tells the speaker “I’m listening, keep going.” Repeated as うんうん, it conveys the same nodding-along energy as そうそう (“right, right”) and is especially common when a friend is venting or telling a long story.
The single most important rule with うん: it is strictly for friends, family, and close peers. Using it with a teacher, a customer, a senior colleague, or anyone you address with さん will come across as rude or shockingly immature — always switch to はい in those situations.
In text (LINE, DMs, SNS), うん is safe with people you’d use first names with, but even then, some people find it too blunt in writing. Adding ！or a softening particle like うん、そうだね helps. With anyone you’re not completely comfortable with, default to はい even in casual digital messages.
Everyday use
「明日、映画行く？」「うん、行く！」
“Ashita, eiga iku?” “Un, iku!”
“Are you coming to the movies tomorrow?” “Yeah, I’m in!”
Casual / Social Media
「もう家ついた？」「うん、今着いた」
“Mou ie tsuita?” “Un, ima tsuita.”
“Did you get home yet?” “Yeah, just got in.”
Formal / Cultural context
「田中さん、この書類を確認しましたか？」「はい、確認しました。」
“Tanaka-san, kono shorui wo kakunin shimashita ka?” “Hai, kakunin shimashita.”
“Tanaka-san, did you check this document?” “Yes, I have checked it.” — Note: saying うん here instead of はい would be a serious breach of workplace etiquette.
Japanese conversation relies heavily on 相槌 (aizuchi) — the practice of giving frequent verbal and non-verbal signals while someone else is speaking. Where English speakers might stay quiet and nod, Japanese speakers actively respond with うん、うんうん、そうそう、なるほど、or へえ throughout a conversation. Silence on the listener’s end can feel cold or inattentive, so these small sounds carry real social weight. うん is the most unguarded of these signals, which is why hearing it from someone tells you they feel genuinely at ease with you.
The range of aizuchi words each carries its own flavor: うんうん suggests warm, nodding agreement; そうそう (“right, right”) shows enthusiastic alignment; なるほど (“I see”) signals that you’re processing new information; and へえ expresses mild surprise or interest. Learning to sprinkle these naturally — especially うん and うんうん among close friends — is one of the clearest signs that a learner has moved beyond textbook Japanese into the rhythm of real spoken conversation.