na-adjective, noun
Describes a person, sense, or reaction that is quick to notice or respond to stimuli, changes, or subtle cues. Can be used positively (keen awareness) or negatively (easily affected).
彼は音に敏感で、小さな物音でも目が覚める。
He is sensitive to sounds and wakes up at the slightest noise.
肌が敏感なので、新しい化粧品を使うときは注意している。
My skin is sensitive, so I'm careful when trying new cosmetics.