Uta∽Kata: Shotou no Futanatsu
English title: Utakata: Summer Pair of Early Winter
Japanese title: うた∽かた - 初冬の双夏
Type: Special
Episodes: 1
Source: Original
Genres: Drama, Fantasy
Studios: HAL Film Maker
Producers: Bandai Visual, gimik
Duration: 24 min
Rating: PG-13 - Teens 13 or older

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)