Arata Kasuga's world is not quite what it seems, a fabrication put together by a powerful Grimoire left behind by his cousin Hijiri, designed to protect him from himself. Unknown to him, Arata holds the potential to become the next magic king, a power which is subconsciously ripping the world apart. After being 'saved' by Lilith, a teacher from the Royal Biblia Academy, Arata chooses to ignore her order to hand over the Grimoire and instead to become a student at the academy. Now trying to work out what he is and where Hijiri has gone, the only advice Arata has to go on is to assemble the Trinity Seven, the academy's top mages, to help him out.

Issei and Arata, both perverted protagonists, though debatably Arata is somewhat more proficient at the art. The two are quite incapable of hiding their carnal desires and have no trouble getting into a myriad of erotic encounters. Both of them are of course the de facto most powerful character in the series, managing to boost their way out of any situation. The main difference between the two is largely that Trinity Seven considers itself a bit classier than High School DxD, with a more nuanced art style and way of presenting its ecchi moments. If you liked High School DxD then check out Trinity Seven for a different twist on a similar idea.

Basara is a lucky guy, acquiring two cute new step sisters just as his dad leaves on a trip. Only these little devils aren't what they seem, revealing themselves to be the daughter of the demon king and her succubus aide. But Basara has his own secrets, being a former hero himself, as the son of one of the world's most powerful heroes. After finding out that the two girls are being hunted down by their own people, Basara agrees to protect them both. They are his sisters after all.

Shinmai Maou no Testament is basically High School DxD 2.0, you've got demons, magic battles, borderline hentai, everything you could ever wish for in an ecchi series really. The only real standout difference is the characters' personalities, with Basara being much more mature than Issei and the girls varying a lot as well. There isn't much more to add really, it feels very much like Shinmai Maou no Testament was adapted because of High School DxD's success with the two being so similar in every regard. If you've run out of High School DxD to watch then we'd recommend moving straight on to Shinmai Maou for more excellent ecchi action.

When strange robot-like invaders appeared from another world and humanity's weapons prove to be pathetically ineffective at putting up a resistance, it's time for a change of tactic. Schools like Ataraxia defense academy are now training Heart Hybrid Gear users to fight the alien menace, with our protagonist Hida Kizuna being one of the latest recruits. But Kizuna is no ordinary HHG user, with his special talent being to power up other users via erotic methods. Now on a team with the academy's top 3 beautiful girls, it's his job to keep them in prime condition.

Masou Gakuen HxH is next in the line of action harem shows that we've seen a lot of recently, but if there's one thing it does better than many of it's predecessors, it's hot ecchi action. Rather than being powered up by girls as in Issei's case, we have Kizuna powering the girls up, via the same lewd methods. Masou Gakuen HxH is certainly steamier than High School DxD, with most of the scenes being one slip away from an 18+ rating, though DxD does provide some loli fan service that HxH is currently missing out on.

Masou Gakuen HxH particularly focuses on girls with obscenely large chests, so if the Rias-Akeno double team combo was one of your favourites, then the HxH maidens will not disappoint. Masou Gakuen HxH is one of the newest series that any fan of High School DxD should be able to enjoy.

Akuto Sai's new high school life takes a brick to the neck with the revelation that he's prophesied to become the next Demon King, something which many other students are obviously concerned about. With his plans to become a high priest very much out of the window, his new focus is to control his emerging demonic powers and to try and use them for good rather than evil. With a government robot girl, a quirky redhead, and a strict samurai tsundere constantly keeping an eye on him, it's certainly in his best interests to not turn into a mad demon lord.

Once again proving demons aren't so bad afterall, Sai is the series' Issei, with his overpowered demon abilities and friendly dragon buddy. Ichiban Ushiro no Daimaou has a bit of an older feel to it than High School DxD, with the ecchi being delicious but not quite as over the top. Besides ecchi the two both have some great action throughout, with plenty of weird creatures, magic, and ripped clothing. Wait, we're back to ecchi there. Wrapping itself up quite nicely in 12 episodes, Ichiban Ushiro no Daimaou is one of the few harem series to give a feeling of closure, so if you're after something with magic and cute girls that's a bit shorter than DxD you should give it a shot.