I'm hard-dropping that one after the last couple of episodes. Killing innocents on purpose and without remorse to get revenge on a third party is just Not Acceptable.

I find Overlord a lot less disturbing, possibly because Ains himself isn't directly responsible for a lot of the most heinous stuff (his servants tend to be a lot nastier than he is, and seldom tell him exactly what they're doing), and possibly because most of the people he ends up killing aren't total innocents and are usually given a chance to fight back. (Plus, we have no idea what being stuck in a lich's body does to the human psyche, so he has at least that much excuse for the evil he does do outright and knowingly.) And it was obvious from the beginning that Overlord wasn't taking place in a nice world.

Buchigire Reijou, on the other hand, started out in a much lighter register, as typical villainness stuff where most of the nastiness is social and political and what combat there is doesn't get particularly gory, and then the protagonist suddenly went full Kingdoms of Ruin on everyone's asses without even nearly enough buildup to justify it. It just doesn't work.