Director Mika Ninagawa is a fan of the "xxxHolic" manga comic, and had wanted to adapt it into a movie for ten years.
Akagumo is an original character created for the film, and does not appear in the "xxxHolic" manga comic.
In an interview, Ryunosuke Kamiki (Watanuki) and Hokuto Matsumura (Doumeki), when asked what they would wish for, respectively said they would wish to be taller and have better health.
Kô Shibasaki (Yuko Ichihara) and Ryunosuke Kamiki (Watanuki) last worked together in Dr. Coto's Clinic (2003), when Kamiki was in elementary school.