18+ Nagasarete Airantou

Ikuto Touhohin just had a 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. Beautiful girls. Stranded on an island with only girls, no electricity, gas, radio, television, like he was back in the stone age.

(Source: AniDB)