Promare, the first full-length feature film from Studio Trigger, will be in theatres across North America this September. The plot of Promare centers around a fighting mecha service tasked with protecting the world from a destructive force called the "Mad Burnish" according to Crunchyroll.
With a special, two-day premiere event scheduled on September 17th and 19th, Promare will release nationwide on September 20th. While there isn't an English trailer available just yet, it's reasonable to expect that one will be forthcoming rather soon. In the meantime, perhaps another look at the Japanese trailer is in order.