Suiei Kyoushitsu ~Fuyu de mo School Mizugi~

Touya, the protagonist who can't swim for life, secretly starts attending swimming lessons to keep a promise to go to the beach next summer he made to his stepsister, Naho.
Due to renovations at the swimming school he usually attends, Touya and Naho participate in a swimming camp open only to those who wish to attend.
The instructor for the camp is Kotone, the daughter of the swimming school's owner and a former national swimming champion. She's a year older than him and attends the same school.
Kotone has harbored feelings for Touya since he enrolled, and during this camp, she actively tries to win him over.
Will Touya be able to swim 25 meters by the end of the camp?
And what will become of Touya's love life...?

[Translated from the official site]