Ackman is a demon kid who collects souls, and Akira Toriyama decides the entire premise is absurd enough to just go full cartoon violence slapstick for 25 minutes straight. The OVA doesn't pretend to be anything except permission to watch a 200-year-old gremlin wreck things with rubber-hose energy and zero consequences. It exists in that specific mid-90s space where a manga god could make something purely for fun, purely for chaos, and never worry about it needing to mean anything.
Ackman is a pint-sized demon who's been collecting souls for two centuries, and he's pretty good at his job. Working under the Dark Devil Lord's orders, this ancient child bounces through the world causing mayhem and reaping unfortunate humans for the underworld's benefit. The catch: Ackman's methods are chaotic, crude, and hilariously unpredictable. What should be straightforward soul-harvesting assignments turn into slapstick disasters where his targets escape, outsmart him, or just plain refuse to cooperate. The comedy comes fast and unfiltered. This isn't sophisticated humor. Ackman relies on physical gags, crude jokes, and absurd situations that escalate without warning. The tone swings wildly between violent action sequences and pure cartoon buffoonery, never settling into one mood for long. If you want something short, trashy, and entertaining that doesn't pretend to be anything deeper than it is, Ackman delivers pure early-90s nonsense. It's exactly what happens when a studio decides to make something deliberately ridiculous and commits fully to the bit.