Exactly how the title of this Spring 2013 light novel-based series corresponds to its subject material is so obscure a scientific reference that the producers felt compelled to explain it in a note at the beginning of the opener: the title is an allusion to the Red Data List, a nickname for a list first produced in the early 1960s by the IUCN (International Union for the Conservation of Nature) which details the threats of extinction to various endangered species. Hence Izumiko's peculiar nature is so rare and prized in the modern era that people like her are effectively an endangered species themselves.

The amount of thought put into this is indicative of the approach that the entire series takes, which is just one aspect of what casts the series in a different light than others whose premises essentially boil down to “girl discovers that she is imbued with a spirit that gives her special powers and has trouble managing it.” Unlike many series of its ilk, this one is a heavy, almost completely serious story told in a slow, gradual progression, one which allows little room for frivolous content because almost every scene figures into its overall story in some way. Even a scene where Izumiko accidentally gets drunk from consuming too much of a liquor-flavored fruit dish (and yes, she eats enough of it to get pretty much anyone her size at least buzzed, so she's not just ridiculously sensitive), the way she acts while drunk has certain implications about the actual nature of her powers. The creepy tone that the series establishes in its inaugural pre-Houjou Academy arc (which covers episodes 1-3) also plays into this, as it goes less for flashy effects and more for a gradual development and detailing of Izumiko's anxieties. Although the tone lightens somewhat as the Soda siblings come into the picture beginning in episode 4, the vague anxiety that Izumiko has about her powers, Hime-gami, and the need to keep them secret even from friends still lingers, leading to the creepier elements occasionally resurfacing.

While this approach is quite effective at developing a setting rich with elements of Buddhist and Shinto mysticism, it is also a very time-consuming one – too much so for a series a mere 12 episodes in length. The end of the series does resolve some important issues concerning the developing relationship between Izumiko and Miyuki, but it does not even fully resolve the story arc it was in at the time and utterly fails to provide any clarification about what, exactly it means for a person, rather than a location, to earn a “World Heritage” designation and why that is important enough to wage a major power struggle at the school over it. The ending also leaves matters concerning Hime-gami entirely up in the air, although it does at least imply that the connection between Izumiko and Hime-gami is not necessarily what the audience has been led to believe to that point. This could partly be the fault of the series only adapting the first five of the six volumes released in the series to date, as a synopsis of the sixth volume suggests that it does explain certain matters better, but that would have required at least three episodes beyond this series' allotted running time or else rushing the story along much faster. Given those two options, the former is preferable even if not satisfying.

P.A. Works and background wizards Studio Easter are up to their usual high-quality teamwork on the production front, which includes some gorgeous mountainscape shots (one scene where Izumiko is dancing on a mountaintop is especially impressive), vividly detailed depictions of the Tamakura Shrine and its approach, and spirit realms which have just the right touch of otherworldly quality. Some of the kimono patterns worn at certain points by Izumiko also dazzle, especially compared to the darker and more subdued general color scheme. She is also amazingly pretty when her hair flows unbraided, though nearly all of the characters are attractively designed and rendered. The few action scenes in the series are not quite so robust, but lighting effects, the CG-generated fields of coruscating dark energy that Izumiko sometimes sees around inhuman individuals, and the regular animation are quite solid. Despite virtually no fan service and a minimal amount of graphic content (outside of episode 12, the series has little actual violence), the content can get dark and intense enough that it is probably not appropriate for younger viewers.

The musical score typically matches the somber and subdued look of the series, though it can take on heavier and more dramatic sounds in scenes of greater tension. It is generally used lightly, however. Neither the opener nor the closer is especially memorable, but the delicate performance of Saori Hayami (Saki in Eden of the East, Ayase in Oreimo) is in bringing to life the low-key, slightly pouty bundle of anxiety that is Izumiko. Also listen for popular veterans Jun Fukuyama, Rie Tanaka, Rie Kugimiya, and Romi Park in significant supporting roles.

Ultimately Red Data Girl shows a bit more potential than it actually lives up to, as early on it looks like it could be one of the year's best series. It instead settles for merely being a good series by neglecting to fill in a few crucial gaps and provide a sufficiently satisfying wrap-up at the end.