Mizu ni Nuretara Ecchi no Aizu!? Hatsujou shichatte Ii desu ka?

Misaki is a girl who is plagued with a condition that she can't tell anyone about... whenever her body gets wet, she becomes uncontrollably aroused. Every day after her bath, her body begins to ache hotly... One day, her handsome childhood friend and crush, Yuuto, asks her to become the manager of the swimming club. This definitely won't end well! But despite her better judgement, Misaki is unable to turn him down. Immediately after joining, the other club members douse her in water, and her body starts burning up in front of Yuuto...

(Source: Renta!)