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~を境さかいに: meaning, usage and examples

~を境さかいに means: ever since... / from... onward (a clear turning point).

Updated 9 November 2026 · By the My Senpai team · Spotted a mistake? Tell us

Examples

1. あの事故じこを境さかいに、彼かれはすっかり人ひとが変かわってしまった。

   Ever since that accident, he has become a completely different person.

2. 2000年にせんねんを境さかいに、その技術ぎじゅつは急速きゅうそくに普及ふきゅうした。

   From the year 2000 onward, that technology spread rapidly.

3. 十月じゅうがつを境さかいに、朝晩あさばんはぐっと冷ひえ込こむようになった。

   From October on, mornings and evenings have become much colder.

4. その日ひを境さかいに、二人ふたりは口くちをきかなくなった。

   From that day on, the two of them stopped speaking to each other.

When to use it

Marks a clear dividing line, a date or an event, after which a state changed. Example: その日ひを境さかいに、彼かれは酒さけをやめた (from that day on, he stopped drinking). Used for personal changes, trends, weather and statistics where there is a clear before and after.

Nuance

Neutral to written. The second clause describes a change of state or trend (変かわった, 増ふえた, 冷ひえ込こむようになった). It focuses on the line itself, not on the intention, so the change may be good or bad and not chosen.

Compare

を機きに stresses using an event as a chance for a deliberate decision: 退職たいしょくを機きに田舎いなかへ移うつった. を皮切かわきりに starts a series: 大阪おおさかを皮切かわきりに全国ぜんこく展開てんかい. を境さかいに is simply "before X and after X are different." てからというもの adds personal emotion to a similar change.

Tip: Imagine a border line on a timeline. If the sentence is about a before-and-after difference, を境さかいに fits.