The Tokyo Project OVA トウキョウ バイス [1988]

It all starts when an injured man wanders into a concert. He hands a floppy disk to Junpei, a college student in the audience, who he asks to deliver the disk to a friend just before he dies. The boy then begins a search for the retriever of the disk, however, there are other people after this disk as well. This puts him and his friends in danger as havoc breaks out and the chase begins. Junpei Toma, Akira Nagure, and Keiko Yamasaki, a trio of college students, are members of the detective club Rats. The four, including Junpei's younger sister Kumiko, are involved in the black conspiracy of a giant company by keeping a floppy disk containing confidential data because Junpei suddenly took care of it. The data is important for the development of the next land weapon, and Junpei will soon confront the new weapon, the bipedal walking mecha, Doru No. 3.