Kenkou Zenrakei Suiei-bu Umishou EP1 - Churaumi!

This introduces the characters and the setting. On the beach, Momoko Orizuka and Kaname Okiura are relaxing when a houseboat comes in. On that houseboat is Amuro Ninagawa. She is holding a 3-foot-long (0.91 m) shark in her hand. She comes in and offers the shark to Momoko. Momoko refuses, saying she doesn't like a dead shark. Amuro says the shark is still alive. It then springs to life in Amuro's hand and tries to bite Momoko, but ends up tearing Momoko's swimsuit top off. Then Amuro dives into ocean, seemingly vanishing, only to emerge some distance into the waters within seconds, impressing everyone, especially Momoko.