Not necessarily.
CLAMP also did the character designs for another Madhouse production,
Sweet Valerian.
From the August issue of Newtype (click to enlarge):
More character sketches at:
famitsu
mycom
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Information about the movie adaptation from
EigaWiki:
The Shadow Spirit (魍魎の匣, Mouryou no Hako) is a 2007 Japanese movie directed by Masato Harada. The film is based on the second novel in a series written by Natsuhiko Kyogoku about a Shinto priest who runs a book store.
Plot:
In 1952 the mutilated corpses of young women are found in boxes and a strange psychic is thought to be responsible. When the daughter of a former actress goes missing, a private detective, a writer, and a policeman team up with a Shinto priest nicknamed "Kyogokudo" to get to the bottom of the mystery.
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A note about the translation of Mouryou no Hako (魍魎の匣):
魍魎 = all kinds of spirits and goblins
匣 = box