Okaeri! ~Yuunagi-iro no Koi Monogatari~

This is the story of Youhei Oohira, a third year college student living alone in Tokyo. One summer, he returns to Himegima island for his teaching practice. On the ferry to the island he runs into his childhood friend, Nagisa Shinohara, who gets agitated by the fact that he didn't recognize her. While on the island, Youhei meets other characters, mainly girls, where this story of love and friendship begins.

[from MobyGames]