気づく
きづく (kizuku)
to notice, to realize, to become aware of
verb (godan)
Example
彼女は自分の間違いに気づいた。
かのじょは じぶんの まちがいに きづいた。
Kanojo wa jibun no machigai ni kidzuita.
She noticed her own mistake.
Often used with the particle に to indicate what is noticed. Very useful for expressing sudden awareness or realization.