Mermaid is the anime branch of a three-pronged multimedia project under the general name Valkyrie Drive; the other two branches are a PS Vita game and an app-based social game. Its basic structure, setting, and story hold enough parallels to Cross Ange (which was, perhaps not coincidentally, finishing up at the time that this project was announced) that comparisons between the two are inevitable. After all, both are predicated on a special condition which only affects female humans, resulting in the affected individuals being ostracized and forcefully isolated on an island; that this series' concept involves the affected individuals having a power while Cross Ange involved them not having it is really just a minor variation on the concept. Both feature a young woman who is torn from her family and thrown, completely unprepared, into the prisonlike island, both use prominent characters which include an overbearing woman who keeps a bevy of lovers for her harem and a law-and-order-type who wants to keep everything looking good so that they might eventually get off the island, and both involve sexy yuri antics, which in some cases includes overt molestation and at least attempted rape. The two series also, to a certain degree, share a similar mean-spirited tone and both have plenty of high-powered action.

The differences between the two are just as important, though. Whereas Cross Ange focused on a single central character trying to figure things out on her own, this version focuses on a couple, and that does give this series a mildly different flavor. So, too, does Valkyrie Drive much more completely being a fan service-focused series, whereas Cross Ange used such content as more of a complementary element. The battles in Valkyrie Drive are also almost entirely internal, as no clear external foe exists. As a result, the story elements, character development, and even the eventual chief villains here are far more formulaic and limited; this one does not have the breakout in character progression, themes, and storytelling that its predecessor had. Granted, it is also only half the length, but it never gives the impression of heading in a more positive direction, whereas Cross Ange did before its first half ended.

Evaluated entirely separately, this 12 episode Fall 2015 series uses a premise which is really just a thin excuse to have a (nearly) all-female cast whose members actually have compelling reasons to get sexy with each other. Triggering the transformation of an Exter requires stimulating the Exter sexually, with the implication being that the Exter achieving orgasm is required. This means that all manner of French kissing, breast-fondling, licking, and even crotch-rubbing is usually involved, and of course all of that is lovingly-animated to a degree which stops just short of crossing lines into hentai territory. (This also does raise the question of whether having sex just for enjoyment can be a tricky proposition for Exters and their Liberators, but the series never delves into that.) While that presents ample opportunities for fan service, it also turns the transformation sequences into tedious affairs and stretches the “enemy waits around patiently for the transformation to complete” principle beyond the boundaries of suspension of disbelief. This requirement is also occasionally fudged upon or even outright ignored when scenes are too busy to bother with fan service – especially towards the end of the series – so the internal logic here is also shaky.

The story, such as it is, mostly involves conflicts over how the population of Mermaid should be organized and administered, with occasional suggestions mixed in that some shadowy government or corporate body tried to weaponize Armed Virus-infected individuals and that one or more survivors from that program might have ended up on the island. This becomes a major focus of the plot in the last couple of episodes, but even then it is used more to justify why one newcomer is a powermongering ruthless bastard than to create any kind of compelling storyline. Serious effort at character development is sporadic and of limited impact, with main developments of importance being Mirei finding a new purpose for herself in Mamori and Mamori, who at least thinks she's straight even though she's clearly capable of being aroused by women, gradually coming to accept Mirei as a true partner rather than just as a pairing of necessity. One entire episode focuses on Akira, the island's nominal leader, and “his” very transparent secret, but nothing is ever really done with what is learned about Akira's background. Limited background snippets provided about a handful of other characters are largely unsatisfying.

Whatever else is a problem with the series, the visuals usually are not part of it. Studio ARMS practically specializes in racy, action-laden fare (Ikki Tousen, Queen's Blade, Kite, and many others in that vein), and director Hiraku Kaneko also helmed The Qwaser of Stigmata franchise, so them knowing exactly what they are doing in producing racy-to-the-max content is quite evident in the resulting product. In fact, in a purely technical sense this is probably the top fan service title of 2015, and that is saying something given the high level of competition it faced. You get the whole package here (or will, once it is available uncensored), and every single bit of it is either yuri-flavored or (much more rarely) masturbation. Though the series does technically provide the full gamut of chest sizes and body types among its cast, it focuses by far the most on statuesque women with huge breasts; even the petite Mamori is quite well-endowed for her tiny build, though she is, of course, still envious of those who are even bigger. Interestingly for a fan service series, it does actually include a couple of overtly chubby girls, too. Battle scenes have a fair amount of flash and pop, although the series is only slightly above-average overall in that regard; it actually is more impressive in some more basic hand-to-hand combat scenes than in the high-powered fare. Regardless of the type of scene, though, vivid coloring and consistent quality control are regular features.

The musical score is no slouch, either. Most of the score is fully-orchestrated and supports the mood of the scenes without ever coming across too heavily. Opener “Overdrive” by Hitomi Harada (the voice of the villainous Momoka/A3) is a powerhouse on both the visual and audio fronts, enough so that it is well worth a look/listen even if you do not intend to actually watch the episode content. Closer "Ultra Super Hyper Miracle Romantic" sung by the two lead seiyuu is exactly what you would expect it to be with a name like that. Cute, but it has nowhere near the replay value of the opener.

Normally I do not comment extensively on Japanese cast performances, but one merits special mention here. Relative newcomer Mikako Izawa, who is getting her first lead role, gives Mamori an airy voice which may be the single most obnoxious Japanese female vocal style that I have come across in recent memory. It grates on the ears, but then Mamori's character also grates on the nerves, so in that sense I suppose it is fitting. A (presumably eventual) English dub would have to be pretty bad to not offer an improvement. Other performances are unremarkably adequate and Ms. Izawa does do better in singing the closer.

Overall, the animated side of the Valkyrie Drive franchise has very little to offer anyone who isn't enamored of heavy fan service series, especially those which focus on (male-oriented) yuri content and enormous racks. It also has objectionable content in it of a type and degree that is typical for series of its ilk. Basically, if you find the Queen's Blade and/or The Qwaser of Stigmata franchises to be at least tolerable then there is a good chance that this will work for you, too, although the story quality and character development here are decidedly lesser. Otherwise if you want to see this story concept done much better in the long run, check out Cross Ange instead.