約束
やくそく
yakusoku
= promise; appointment; agreement; commitment
約束 (yakusoku) captures something deeper than a simple promise — it carries the weight of a binding tie between people, reflecting how seriously Japanese culture treats mutual commitment.
約束 functions as both a noun and a suru-verb, making it one of the most versatile words for expressing commitment in Japanese. As a noun, it refers to a promise, appointment, or agreed arrangement: 約束がある (yakusoku ga aru) means “I have plans” or “I have an appointment.” As a verb, 約束する (yakusoku suru) means “to make a promise” or “to commit to something.”
The word pairs naturally with two opposing verbs that reveal its moral dimension: 約束を守る (yakusoku o mamoru, to keep a promise) and 約束を破る (yakusoku o yaburu, to break a promise). Breaking a 約束 — especially canceling plans at the last minute — is considered significantly ruder in Japanese social contexts than in many Western cultures, where informal plans may be renegotiated freely.
In everyday use, 約束 covers everything from a casual plan to meet a friend to a formal contractual commitment. The range of meaning means context matters: a 約束 made between close friends about dinner carries different social stakes than a business 約束, but in both cases, honoring it reflects directly on one’s character.
Learners often treat 約束 as only meaning “promise,” but it is the standard word for any scheduled appointment or plan with another person. If someone asks 今日は予定ある？(kyou wa yotei aru?, Do you have plans today?), you can answer 約束がある (yakusoku ga aru) to mean “I have something scheduled” — not necessarily a solemn vow.
Note also that 約束する is a suru-verb, so it conjugates regularly: 約束した (yakusoku shita, made a promise / agreed), 約束しよう (yakusoku shiyou, let’s promise). Avoid saying 約束をする with を in formal or literary contexts — 約束する as a single unit sounds more natural in speech.
約束 combines two kanji that together evoke the image of binding people together. 約 (yaku) means “promise” or “approximately” and appears in words related to restraint and agreement. 束 (soku) means “bundle” or “to tie,” as in tying stalks together. The compound creates a vivid metaphor: a promise is something that ties two parties into a shared obligation, much like binding objects into a single bundle.
Everyday use
友達と明日の午後に会う約束をした。
Tomodachi to ashita no gogo ni au yakusoku o shita.
I made plans to meet a friend tomorrow afternoon.
Casual / Social Media
約束は守ろう。後で後悔しても遅いよ。
Yakusoku wa mamorou. Ato de koukai shite mo osoi yo.
Keep your promises. It’s too late to regret it later.
Formal / Cultural context
先日ご確認いただいた件について、改めて約束の内容を書面でお送りします。
Senjitsu go-kakunin itadaita ken ni tsuite, aratamete yakusoku no naiyou o shomen de o-okuri shimasu.
Regarding the matter you confirmed the other day, I will send you the agreed terms in writing.
In Japanese society, 約束 carries a moral gravity that goes beyond scheduling. Canceling a committed plan without significant notice — especially for social gatherings — is considered a breach of trust rather than a simple inconvenience. This cultural weight stems from the broader value placed on meiwaku (causing trouble to others): backing out of a 約束 forces the other person to reorganize their time and signals that you did not take the commitment seriously. Repeated 約束破り (yakusoku yaburi, promise-breaking) can quietly damage a relationship or professional reputation.
The concept also appears in more solemn contexts, such as vows made at critical life moments — between close friends, within families, or in public pledges. The phrase 約束を守る人 (yakusoku o mamoru hito, a person who keeps their promises) is a sincere compliment in Japanese, describing someone reliable and trustworthy. Conversely, being known as someone who breaks 約束 touches on core values of sincerity (makoto) and dependability that underpin much of Japanese interpersonal culture.