Update: Official English website for Shinpei Hayashiya's DEEP SEA MONSTER REIGO (SHINKAIJÛ REIGÔ), w/ Taiyô Sugiura, Mai Nanami, Yukijirô Hotaru, Susumu Kurobe, Ukon Ichikawa, Yôji Tanaka, et al.

The official English website for Shinpei Hayashiya's Deep Sea Monster Reigo (Shinkaijû Reigô) has just gone online, and there's a downloadable English-subtitled trailer for the movie on it.

According to this page for Deep Sea Monster Reigo on the website of Aqua Geo Graphic K.K. (Akua Jio Gurafikku K.K.), the movie's principal cast is as follows: Taiyô Sugiura, Mai Nanami, Yukijirô Hotaru, Yôko Kanda, Yui Nirehara, Mubu Nakayama, Masayoshi Okada, Kôki Hisaka, former Representative Kôki Kobayashi, Toshihiko Yamamoto, Akihiro Shimizu, Makoto Inamiya, Hiroshi Shimizu, Yûma Kusakawa, Mickey Curtis (Mikkî Kâchisu), the late Yumika Hayashi, Isamu Ago, Yôji Tanaka, Susumu Kurobe, and Ukon Ichikawa. It appears that former Prime Minister Yoshirô Mori, who early last year was considering playing an admiral in the movie (see here), decided not to be in it.

Deep Sea Monster Reigo was shot, in part, in Chuuk (a.k.a. Truk), Federated States of Micronesia (FSM).

For more information on Deep Sea Monster Reigo, see Twitch's fourth, third, second, and first articles on it.

Deep Sea Monster Reigo trailer (Japanese w/ English subtitles; downloadable 11.7 MB WMV file)
Deep Sea Monster Reigo official English website
Deep Sea Monster Reigo official Japanese website