The following description is from Giant Bomb
Demon Child Zenki: Battle Raiden is a game based off of the popular (at the time) manga series by Kuroiwa Yoshihiro,
which ran from 1993 to 1996 and spawned several games. This title is the only action/platformer related to the license.
The player takes control of Zenki, a large and powerful demon imprisoned in servitude long ago by Enno Ozunu, the
ancestor of the female lead, Enno Chiaki. Zenki is revived from his long sleep by the re-appearance of hyoi no mi
( ŠćĹńżŁŃü«ň«č, or "seeds of dependence" evil seeds that bind lives to the desires and needs of the physical world.
However, to help keep him under control Zenki's powers are sealed the majority of the time, leaving him in a small
and weak child's body.