Omnis

You were walking down the street in the rain, heading back home. You were soaked to the bone, having forgotten to take an umbrella in the rainy weather. You were walking briskly, trying to escape the bad weather as quickly as possible, when you accidentally stepped on some girl's foot. You apologized to her, but she timidly stammered "sorry!" and ran away, slipping in the process. And the first thing that entered your field of vision was... a fish tail? You approached the girl and decided to help her up, wondering whether to ask about her peculiarity or not.