(Taken from animenewsnetwork.com)

Name: XXXHOLiC: Manatsu no Yoru no Yume (Midsummer's night dream)
Release in Japanese theaters: August 2005
Release on Japanese DVD: February 25th, 2006

Animation Production: Production I.G
Distributor: Shochiku, Co. Ltd.
Director: Tsutomu Mizushima
Screenplay: Jun'ichi Fujisaki, Yoshiki Sakurai
Storyboard: Tsutomu Mizushima
Character Design: Kazuchika Kise
Art director: Shuichi Hirata
Animation director: Kazuchika Kise
Director of Photography: Hisashi Ezura
Art Setting: Takashi Watabe
Audio Director: Kazuhiro Wakabayashi
Colour Design: Sayuri Yoshida
Editing: Taeko Hamauzu
In-Between Check: Chieko Ichimanda
Prop Design: Minoru Ueda

(translated by Little Harlock Newslog)
One day Yuuko receives an invitation by a mysterious addresser for the holding of an auction. A lot of hard edged collectors have been invited for this auction held at an old-fashioned European style building. However once Yuuko and the fellow invited collectors arrive the mysterious host of the auction doesn't show up.
Moreover it seems that soon one after another the guests (the collectors) mysteriously disappear and even more strange events happen on the auction night. What happens and who on earth actually is the host of this whole "party"?