Maken-ki!: Natsu Da! Mizugi Da! Gasshuku Da!
マケン姫っ! 夏だ! 水着だ! 合宿だ!
The first semester ends at Tenbi High School and the summer holidays begin. Ooyama Takeru, his childhood friend Amaya Haruko and the other girls are off to a Maken-ki camp on the southern islands.
But at the beach it is not all fun and games, harsh training awaits Takeru, who wants to be able to protect the one he loves...
(Source: foo2 of AniDB)