Spy Kyoushitsu

If you enjoied "Ansatsu Kyoushitsu" you could start watching "Spy Kyoushitsu" Here are some similarity of the anime I like: 1. Both have an overpowered teacher you have to beat 2. Both have some sort of classroom 3. Both contain students who are washouts and the "losers". Since only the first episode is out, I can't tell much about it. But I have the feeling you might enjoy it, if you like any of these aspects. In my case, it really worked out. I like these concepts. Recommendation goes in both ways, basically. 

Both these shows center on a small group of young female spies who want to shape the world better after dealing with trauma that comes with war. Both shows go to great lengths to really establish setup their missions of espionage and go show their execution. Both shows are fairly serious with some light moments of comedic relief and both evoke a period setting, with Princess Principal going for a steampunk turn of the century feel and Spy Room going for a post-World War I look with its setting. 

Both animes are related to crimes and investigation but the difference is that the anime is talking about spies and the other is talking about detectives. Plus, the helpers/the students of the leader MC in both animes are dealing with problems Also, both animes can be considered as romance. 

The style is very similar. In both, girls learn to fight an enemy and the relationships between the characters are very good.  

Very similar feel with a group of girls undertaking covert missions and are led by a strong male. 

A healthy dose of spy girls in training but with a legendary spy as their teacher instead of a traditional schoolteacher. 

It doesn't sound very similar but when you heard it, its definitely sound similar especially some of the main cast. And instead of fighting goblin, we'll be fighting warcrimes 

Different in their setting and genre, shows that are almost identical to each other in the general idea of ​​"a professional young adult male professionally trains memorable and diverse loser girls in an attempt to achieve their goals". Both protagonists are quite handsome and charismatic, unconsciously gets girl love but for various reasons, awkwardly unaware of their affection. You'll also find some of the girls' gimmicks quite similar, such as the playful narcissism of Honda and Lily, or the tomboy-ish machismo of Sibyl and Tada. Also, due to the number of girls, both shows have episodes dedicated to certain characters separately.