When did Kagura wear the angel outfit in GinTama?

Kagura never wears an angel outfit in Gintama. She does have a few outfits that could be described as "angelic" in the sense of being pure white and flowing, like her Shinsengumi uniform.

However, there is no specific instance where she is explicitly dressed as an angel.

Is there a specific scene you are remembering? Maybe we can clarify what you're thinking of!