WXIII Kidou Keisatsu Patlabor

When the level of Labor accidents begin to escalate around Tokyo Bay, police detectives Kusumi and Hata are assigned to investigate. What they discover leads to a series of government cover-ups, conspiracy concerning a new biological weapon entitled WXIII-Wasted Thirteen and a tragic, personal connection to Hata. The only hope to stop this threat is to cooperate with the military and lead WXIII into a showdown with the Labors of Special Vehicle Division 2.

(Source: Anime News Network)

This Movie is a Side Story that takes place in between Patlabor Movie 1 and 2