This and Maou-Sama very lightly reference each other, but aren't really required to understand each other. There's a couple of cameos from each game in the other (the MCs meet near the end of this one, presumably will have that scene from the Maou-Sama's perspective when that specific ending is released, and if the third game ever does get made presumably we'll see the scene from his perspective as well at some point, and then there is one of the girls from Maou-Sama that is like an exposition dump character in this game - and not an LI because that would be cross game NTR and we ain't having none of that here - and a couple of girls that seem to have originated in this game make a few appearances in Maou-Sama in a similar role)
But yeah, it's definitely super dense, between the dozens of LIs and several simultaneous plot threads in each game, but they're both mostly just fun nonsense with crazy shenanigans going from one sex scene to the next, honestly, and I always had fun. The stories aren't like, Kingdom Hearts level of confusing at least, lol