JoJo no Kimyou na Bouken - Mugen no Ou

Set between the events of Battle Tendency and Stardust Crusaders in 1973 to 1986, a research group from the Speedwagon Foundation is sent to Antigua, Guatemala under Lisa Lisa's orders to investigate the identity of a serial killer with an unknown power. Their investigation leads them to Fernando Alhorn, a gang leader who has been using the Arrow to amass his own private army.