It has been officially confirmed by Aniplex of America that they plan to release the Kizumonogatari I film is set for release in US theaters February 26th 2016. An english subtitled trailer was also released which can be seen later in the article. The film first is titled Kizumonogatari I: Blood and Iron. That film is the first of three films in total and will be releasing January 8th in Japan with an estimated runtime of 60 minutes. Now the second movie is titled Passionate Blood and the final film Cold Blood. The website for the film is in the following link and originally debuted back in 2011:http://www.kizumonogatari-movie.com/. The film is a prequel to the entirety of the series set before Bakemonogatari and the upcoming movie adapts source material from the Monogatari series first season light novel. The light novel would release 6 volumes between the dates of November 1st 2006 and July 28th 2010.
Now below is a plot summary of the series quoted from MAL:
The story centers on Koyomi Araragi, a third year high school student who has recently survived a vampire attack, and finds himself mixed up with all kinds of apparitions: gods, ghosts, myths, and spirits.