Big Human on Campus is a crossover between Rosario + Vampire...and Ranma 1/2. And it has a lot of Ranma flavour and is also very much a comedy, not serious even remotely. Some examples of the fun: Ranma regularly states that he is a human to everyone, with no one believing him because of how strong he is, which results in most students being afraid of Nekonome Shizuka because Ranma is scared of her, and Richard of Looking for Group is a teacher at the school.
Most of my recommendations will be...not serious or dark in any way shape or form.