Nanatsu no Maken ga Shihai suru

School setting. Magic academy. Somehow swords are important despite the magical setting. The plot entirely revolves around a promise MC's has made to a woman. Labyrinth/Dungeon is a mysterious place where a lot of stuff happens. In the first few episodes we see teachers with disdain for MC. Also there's a rivalry with a smug pompous jerk guy who is quickly put in his place. Teachers are hiding something. MC has a singular goal on his mind. 

- completely different tone yet both evoke and remind u of the atmosphere of harry potter when watching - Mashle is a pretty clearly intended parody of it, while Nanatsu no Maken is more of a serious/edgy/modern take on it - both revolve around a group of teenagers becoming friends in a magic school, and both have very well(especially considering current standard <_<) designed characters where pretty much whole main cast feels meaningful and not just like one-dimensional different haired and/or different boob-sized cardboard cutouts - both have elements of mystery - both have wonderful and rly fitting soundtracks - Mashle focuses way more on its protagonist Mash, while Nanatsu no Maken doesn't really have a single main protagonist (one could say Oliver is one but if we consider actual screentime and development he's gotten barely as much if not less than some other from the main cast at least so far) read more 

These anime may see a lot far away from COE but trust me, it gets more and more similar from 7th episode. Some of them are: Both leads have a hidden agenda Both leads are quick thinkers and analyze the situation completely Here, one may not be a tsudere but he does has a very scary side of him just like ayanokoji..... 

MC of this series has a personality similar to Lelouch from Code Geass, possess a very special/powerful ability, revenge-driven.  

The vibe of the show is very similar in my opinion, with the world that we as the audience do not know much about and the dark and twisted norms seem so far. 

Story takes place in magic school located in Europe/European styled country, but at least one of main cast characters came from Japan/Japan styled country and learns some cultural differences. Male MC objective of coming to this school is revenge. 

Same creator for the original series. Both have are magical battle focused with a more serious and darker tone to it.