E4. My Little Sister's Rival Can't Come to Japan

When Kyousuke comes home from school and opens his door, he finds a young, naked girl who just got out of the bath. Kyousuke is completely shocked, but the young girl is Ria, Kirino's roomat from when she studied abroad. She's staying with the Kousaka family while she's in Japan, but the innocent young girl asks Kirino and Kyousuke to take her sightseeing.