I'm a librarian who loves anime, manga, and reading a wide variety of genres.
...Not impressed with this so far, and this is another series that's giving me a "should've been a one-shot" vibe.
Basically, Satan and his demonic minions are terrible but mostly presented as jokes. They're easily manipulated and not so much concerned with achieving world domination as they are with enjoying themselves while they're trying to achieve world domination.
The truly evil one is Satan's human secretary. She's efficient, completely unflappable, and has apparently been planning world domination for years. Within hours of being brought before Satan, she negotiated herself from "human slave" to "paid employee with a conveniently nebulous position in the demon world's new organizational chart." If it weren't for the fact that the demons have more of a conscience than she does, she'd accomplish world domination by the end of this volume. I like her efficiency and the fact that she doesn't take crap from anybody, but she is so coldly evil that I can't root for her.