Tsukune somehow manages to get sent to a monster high school because he fails at getting into any other high school, period (despite being average as opposed to a loser.) He runs into a cute girl named Moka, literally, who then greets him and sucks his blood. The two become friends, and soon he's taking classes, hoping none of the other monsters find out he is human, or he's dead meat.
This is bad because every single story follows the same plot.
1. A new person appears.
2. New person is bad/evil and tries to hurt Moka, Tsukune, and friends.
3. Tsukune rips off the Rosario sealing Moka's powers.
4. Moka's true self curbstomps the other person.
Every single story in the volume.
What's worse is you could just rip the whole monster thing out, and nothing would be lost. Moka is a vampire but she doesn't sleep in a coffin, seems to be fine with the sun, and really only is vulnerable to water (which her powered up self ignores fine.) It's just a tired, cliche, magical high school harem story.