Kirari☆Nangoku Komugiiro ~Shiofuki Paradise e Youkoso!~

Summer holiday! However, the main character and some girls are left behind on the island because all other people have gone out of the island to run away from eruption. Like this, his paradise life starts. One day, they find a water fountain. However, the water makes them sexually aroused once they drink it. But they have to drink water to survive. Once they drink it...