おっ

interjection

oh; oops

Casual exclamation of mild surprise, realization, or a small mistake. Often used when noticing something or making a minor error.

• おっ、もうこんな時じ間かんか。

  Oh, it's already this late.

• おっ、ごめん、ぶつかっちゃった。

  Oops, sorry, I bumped into you.