The High School DxD franchise has become the current standard-setter for harem series, especially action-oriented ones with supernatural elements, so the appearance of imitators in that sphere is hardly a surprise. This awkardly-named anime series, based on a light novel series of the same name, aims to horn in on the same territory, or maybe even one-up the DxD franchise by correcting perceived flaws in the original premise and pushing the fanservice even further. That's a tall order, and while the series largely succeeds at being more lascivious than its predecessor, it fails by comparison at everything else.

The basic premise of the series flips the power structure at the core of DxD without changing the roles, which may be its fatal flaw. Both series feature busty redheads who are potentially powerful devils, but whereas the male lead in DxD is initially hapless and acts at the whim of his devil lady, Testament's male lead is a powerful warrior who becomes a dominating figure from the start. Making the harem lead strong and aggressive is a risky maneuver, since he can't as easily function as a self-insert for viewers, but that could also be a fresher angle for some harem fans. Forcing Mio to become meekly submissive might also have its appeal for some audiences, but it also kills any hope of developing sexually confident aura that DxD so heavily used to its advantage with Rias Gremory. To balance out the machismo of this protagonist, the series greatly reduces his libido to the point where he has to be pushed into doing anything sexy. That may have been necessary to keep the character dynamics from being too creepy, but it also makes him less realistic. Adding Yuki into the equation later doesn't impact this blander chemistry, as she's simply the boilerplate assertive counterpart to Mio's meekness.

One factor saves the character dynamics from complete mundanity, however: Maria. As the saucy succubus who always seems to play the most perverted angle in her quest to protect Mio (though not necessarily her chastity), she's a delight as a fanservice-driven character. Many other harem series have attempted this kind of character, but Maria refines those traits to perfection, paired with a personality that easily slides between serious and mischievous and a place as the only female character in the series who regularly smiles. Both the original writer and director Hisashi Saito seemed to realize her potential, as she gets the best outfits and the best lines in the series. She also proves to be a capable fighter, which is surprising since succubi are not traditionally known for taking that role in anime. The series is almost worth watching just for her.

On the storytelling front Testament follows DxD's lead by having a substantial plot from the start, a welcome trend in harem series over the past few years. “Substantial” does not necessarily mean “complicated” in this case, as this is still a straightforward story about Basara getting to play the heroic big brother by protecting Mio from assorted threats, whether they be ambitious demons or the Hero Clan. Along the way, the master-servant pact he forms with Mio (and later Yuki) provides all manner of excuses for racy scenes, as one consequence of a servant defying the pact is to be overwhelmed by horniness, to the point that the master has to force the servant to “submit” to relieve the effect. Most typically this involves getting the servant to achieve orgasm, perhaps even multiple times if the servant doesn't initially see that as a submission. To avoid actual sex in the series, this generally means a whole lot of intense fondling, stroking, and breast sucking, in scenes that go beyond all but the most intense fanservice anime.

Though the series does have a substantial action component to complement all of the harem elements and fanservice, that isn't its strength; it also loses by comparison to DxD in that regard. The moves and powers on display are entirely ordinary for supernatural battle fare, with little real creativity in powers or battle choreography. The sole exception is once again Maria, who somehow manages to throw convincing punches and kicks despite her stripper outfit. Mediocre animation quality also hobbles the series, along with pacing that regularly results in too-long exposition in inappropriate places and some awkward episode breaks.

Clearly the lion's share of resources went to animating breasts being fondled. Character designs also stand out more than normal, with Basara being much more buff than your typical male harem lead and Maria looking enticingly sleek. Body types for the female characters come in a wide enough range to satisfy most tastes, and this uncensored version provides detailed nudity and undergarments on a regular basis. The action content can get pretty graphic, but blood and gore are not common or significant enough to be worth much concern. Overall, the artistry rarely impresses beyond the fanservice content, with the sharpest visuals just being in the opening theme.

The musical score doesn't consistently impress, either. The soundtrack is at its strongest in some late scenes which feature dramatic orchestration and vocals, but early on it fumbles around with more rock-infused themes. Opener “Blade of Hope” is a sharp number but more for the visuals than the song, while closer “Still Sis” is a suitable closing complement.

The English dub for the series is provided by Bang Zoom! Entertainment under the direction of Wendee Lee, who voices the school nurse and some minor roles. It's an adequate but wholly unexceptional effort, with no performances standing out in either a positive or problematic way. That being said, Lauren Landa deserves some acknowledgement for not overplaying all the sexy moaning she has to do as Mio.

The DVD/Blu-Ray combo pack is being distributed by Funimation. It includes the OVA episode “The Hard, Sweet Daily Life of Toujou Basara,” which is a pure fanservice follow-up to the season, most notable for prominently featuring the school nurse getting friendly with Basara in the second half. The discs also include clean opener and closer and a set of six subtitled-only shorts called “Maria's Secret Videos,” which are narrated highlights of major fanservice scenes. This added commentary isn't amusing enough to make them worth watching separately.

Overall, The Testament of Sister New Devil is passable as an extreme fanservice series, but it gets easily outdone by its competition in most other senses. Still, it was successful enough that a follow-up season did air and will presumably also show up on BD/DVD a few months down the road.