Olive manages to kill Lucifon, and is cursed to take his place as the ruler of the Underworld.
Fighting Reputation: 300
Magical Reputation: 200
A simple route to this ending is to make her take a three month magic course, make her train in combat until her combat skill and attack max out and then beat the fools who challenge her in the street until her magic and fighting reputations are high enough. Enough sin is trickier... make her main job the hunter. That increases her sin by half a point a day and might be sufficient on its own. If that is not enough, then get her faith below 20 (stepping into the Sleazy Bar just once should do that) and then send her to Lucifon's party in the desert. If her faith is below 20, then she will accept his drink which makes her sin go up by 80 each time.
The required fighting and magical reputations are not that high. It looks like any old knight from the castle is tough enough to overthrow Lucifon. Look on the bright side though... that image of her looks much scarier than Lucifon ever did!
- Even though the game considers this a bad ending, many fans don't see it as such because of Olive achieving immortality and power over Hell.