Titre original : Horror!? Summer Island
After Orihime gives Akari and the others a day off for summer vacation, Naoto arranges for them to spend a day on an island, which turns out to be the same island Akari faced her hellish boot camp. While camping out under a squall, Sumire shares a rumor about a mysterious ape man, which the girls start to believe after both Naoto and the boat go missing somewhere. As the girls go on a search for Naoto, finding several of his items along the way, they eventually find a group of monkeys who had rummaged their luggage. Naoto safely returns afterwards, having taken the boat to retrieve a beach ball Akari had left behind.