Sin: Nanatsu no Taizai

All female harem and shameless, gratuitous fanservice links these two anime. In a sense, 'Sin,' is the spiritual successor to the modern ecchi (not quite hentai, but close) genre. 

*Both are very over the top with the ecchi so if thats your thing I'm sure you'll love both *both involve demons lords and angels *Testament has a single male lead with a ton of girls while Sin has a female lead and only girls all show *Testament has more traditional battles/fighting while Sin has more games/challenges that often involve a "punishment" along with some traditional fights *Don't come in expecting a great story in either, you are here in both for the ( ͡° ͜ʖ ͡°) and if you love it over the top and in your face then I'm sure you'll love both *Lucifer the mc in Sin is very arrogant but likeable and the mc in Testament is the more traditional "i'll protect my family at all costs" hero. I liked them both *animation is good in both when the "plot" is required on screen read more 

- op main character - ecchi demon harem with similar character designs - reversal of roles (demons are the protagonists & help humans to some extend) - similar story points & pacing tbh they are just overall similar - if u like one of them, u'll likely enjoy the other one, although Sin is less story-heavy due to it having only one season 

Both animes are about sin , both are ecchi , its true that sin include more fanservice but both animes are familiar from the charachters and a little from the story , satan is for sin and meilodas for nantsu no taizai  

In both animes, all the characters are girls and women; in Mahoako, there are students who are magical girls, representing good and evil; in SIN, the women represent the virtues and the deadly sins. Both animes have comedy, fights and ecchi; the animes also have YURI and BDSM scenes; the groups of villains are most often the winners of the fights. 

All female cast centric ecchi anime . Plot and Character development is secondary fanservice is primary importance for both the series.  

When you watch both of these anime you'll immediately know , what you're gonna see, girls whom were subjected to such sexual perversion that you can imagine.  

Both Sin and Overlord deal with a prideful and powerful main character who cautiously plan out their next move while they try and usurp or take over the world which they've been thrown into. Along the way they become more knowledgeable of themselves and the world, and they then continue to use that information to progress their own goals. The only big difference is that Overlord starts with a bunch of supporting characters, whereas Sin doesn't.