This is a tool-assisted speedrun. For more information, see http://tasvideos.org/1465M.html
In this port of an arcade game, the eponymous avenging spirit has been summoned by his girlfriend's father to rescue her from a crime syndicate holding her hostage.
As a ghost, the protagonist has the ability to possess enemies with a selection of different abilities, but that's rarely seen in this run.
In order to pull off the rescue, three keys are needed; these are retrieved in this run so as to obtain the best possible ending.