The Weiss Kreuz OVAs technically come after the TV series. Kaori and Akira, sister and brother whose parents were murdered by the American military then said to have died in an accident, are trying to do themselves what Weiss is meant to do. Kaori, a teenage girl who attends the same school as Omi, hacks into the American database while her brother, Akira, goes in to kill the man responsible. Since he is trying to do this Weiss gets a mission to destroy him. Omi, being friends with Kaori, and Ken, thinking that Akira and Kaori are in the right, both refuse the mission. Aya and Yoji, however, accept. This leads to conflict within Weiss.—animenewsnetwork.com