Umiko had been hanging out her little brother lately. It wasn't really her brother, but since the first day they met, they had the deep connection and she was willing to take him under her wing.
"Okay, little brother." Water droplets began to pass by her as she spoke. "Hold your breath."
With that he nodded and a did what he was told. She made a huge bubble around him and he began to float. She waited until he gave her a thumbs up.
"Down you go." and with that, the bubble popped.
Her little brother got up and smiled. "My turn. Get ready, big sis!"
From what you saw, it looked like Umiko was teaching him how to use his magic.