on the lookout

Prepositional phrase

Constantly alert, intent on finding something or someone.

Japanese Meaning

常に警戒して、何かまたは誰かを見つけようとする状態を指す表現

The neighborhood watch was on the lookout for any suspicious activity late at night.

近所の見守り隊は、夜遅くに不審な動きがないか常に警戒していた。

Sense（1）

Constantly alert, intent on finding something or someone.

I'm on the lookout for a good example of a Roman dinar from the 1st century. Let me know if you hear of one anywhere.