Tsubamegaoka Private Academy - All Girls' High School, located just inside the city and has clubs a plenty. From the common ones to some freakishly impressive ones, it varies greatly. It's always okay to make one, no matter what kind of club. It's not uncommon to see students join this school for the sole purpose of making a new club. But what happens when five girls want to make a club and only one new club is allowed? Cahe Detective Club happens!

Ikuto Touhohin just had a last fight with his old man, one that led him to make a rash decision to run away from home. He boards a ship, deciding to take a vacation, but the ship is suddenly hit by a huge storm--one that sends Ikuto overboard! When he regains consciousness, he realizes he is still alive… on some island. An isolated island. An isolated island with nothing but girls and talking animals. Stranded on an island with only girls, no electricity, gas, radio, television… like he was back in the stone age.