After spending their first year of high school in peace and quiet, Haruka and Makoto run into Nagisa, a new student who was a member at a swimming club with them when they were kids.  That swimming club is being torn down, so the three of them sneak in to dig up a time capsule that they buried in the back, which is when they are reunited with Rin, the fourth member of their group who left to study abroad.
Let's start a hot springs club!
Gründen wir einen 
Heiße-Quellen-Club!
¡Vamos a crear un grupo de aguas termales!
¡Venga! ¡Un club de aguas termales!
On n’a qu’à faire ça !
Fondiamo un club delle terme!
Vamos montar um clube 
de águas termais!
Давай создадим такой клуб!