Modern Magic Made Simple: Season 1, Episode 4
Yumiko goes to Misa for help in finding the mage responsible for summoning the Daemons, and soon Kaho and Koyomi have been recruited to help too. It isn't long before their 'investigation' leads them to the local water park, where Kaho tries to teach Koyomi to swim. However, after Koyomi nearly drowns it becomes clear that there is a Genie terrorising the park. As such Misa and the others must stop it before anyone is seriously hurt.