Uta∽Kata: Shotou no Futanatsu
English name: Utakata: Summer Pair of Early Winter
Genres: Drama
Type: Special, Episodes: 1
Aired: Apr 22, 2005
Studio: Hal Film Maker
Source: Original
Rating: PG-13 - Teens 13 or older
Synopsis:
It's now winter in Kamakura. When Satsuki tells her friends that she'd seen Manatsu, Ichika at first doesn't believe it. But on the day before her 15th birthday, Manatsu's mirror fragment inside Ichika's desk drawer mysteriously disappears. That evening, a young girl calling herself "Mafuyu, Manatsu's identical twin" appears before Ichika with a mischievous smirk on her face.

(Source: AniDB)