OVA 1: An old journal is found by Levi and Erwin when they conduct the surveillance operation outside the wall. The contents of "Ilse's Journal" result in some unexpected actions from Hange.
OVA 2: Another story of the 104th Trainee Squad.
OVA 3: Will depict a "memorable episode before the 104th Training Corps became unified."

(Source: Anime News Network)