There really isn't much in the way of story here. Haru, a girl born into a clan, is being hunted by 12 other students, who each have their own reasons for wanting her dead. The characters themselves have no real depth to them, nor do they have any real growth. The only characters you could argue experience growth are Tokaku and Haru. This show really isn't deserving of its "Shoujo Ai" tag, either. If you were looking for Yuri, you probably want to search elsewhere.
The story is marginally episodic, with each episode focusing on one particular assassin. The series lends itself to predictability and you'll soon learn that the episodes pretty much go as follows: Assassin sends in their card, Haru is in danger, the girls do the fighting, Haru and Tokaku win while the assassin learns something about themselves and is expelled from the Class Black program. The romantic subplot in this anime is almost non-existent. It's obvious that Tokaku's reasons behind wanting to protect Haru stems from sexual attraction, yet the show never really explicitly says it outright, rather resorting to the more generic term of "wanting to protect someone precious to them". Imagine the romantic subplot as a jar on a high shelf. Now imagine reaching for it, where you can *almost* reach it but its just that bit too far. That's the romantic subplot in a nutshell. It's almost there, but its never explicitly referred to nor is it explored in any fashion.
The animation is good and the art style is aesthetically pleasing. Non-important characters such as b.g characters are portrayed as black and white, providing an interesting contrast from the main characters. The music is good, invoking the right emotions at the right times.
Akuma no Riddle definitely isn't for everyone, as shown by its relatively average score. However, I enjoyed it and had a fun time. If there was ever a reason to ever come back for a second season, which is unlikely, you can bet your buns that I'll be the first one there to be watching it.
