I did it, I rewatched another trashy anime and actually paid attention and this time it is Diabolik Lovers. I think I might eventually need to get my hands on the light novel, the manga or the games to get some of the answers. Since I do not have access to these at the moment and have not looked at them, I am unsure if the anime was just adapted assuming these key points were already known, or if the explanations did not make the cut due to time constraints. Either way, some points left me confused.
B Gata H Kei, aka Yamada's First Time is one of those anime that I feel bad that I actually enjoyed watching. Despite what the anime is about, it is surprisingly innocent. It was definitely made with a more mature - adults - audience in mind, whether the age restriction agrees or not. This time, the ecchi aspect of an anime is not just there as fan service but as an actual plot device. I'm shocked too.