Pakkon, the son of the Demon King, is sent to the human world by his father to "increase the number of people who do good things because hell is full of bad people. But from Heaven, which is also full, the angel Tenchii comes to increase the number of people who do bad things!　This SF comedy, serialized in Gakken Kenkyusha's "Kakunen Kagaku" from 1985, is based on the short animation "Wonder Bevil-kun" in NHK's children's program and includes an unpublished short story "Tsk, Tsk, Bevil-kun," which is based on the same story as "Sloppy Demon Pakkon."