What it means
とみるや expresses an immediate response made upon observing an event and judging that a certain situation has arisen. It is stronger than a neutral “as soon as” because it highlights the observer’s perception or assessment before the following action occurs. The pattern is chiefly used in formal, written, or narrative Japanese, especially when the response is sudden and decisive.
Usage note
とみるや is literary and is not normally used in ordinary polite conversation. The preceding clause usually describes something that can be observed or reasonably judged; it should not be treated as a purely objective time marker.
Example sentences
雪雲の切れ間から月が現れたとみるや、天文部員たちは一斉に望遠鏡を空へ向けた。
The moment they saw the moon emerge through a gap in the snow clouds, the astronomy club members all pointed their telescopes skyward.
火山の斜面から白煙が立ち上ったとみるや、監視員は