This 2009 movie courtesy of Sunrise was helmed by Kazuyoshi Katayama (Big O, Those Who Hunt Elves) and adapted the six volume manga series of the same name by Yuji Iwahara, who is otherwise probably best-known as the original character designer for the Darker than Black franchise. Condensing 37 manga chapters into a mere 104 minutes of animation (109 minutes with closing credits) necessitated taking some shortcuts, which results in a story which uses essentially the same group of protagonists (the background of Marco Owens is different), the same setting and circumstances, the same major plot twist near the end, and many of the same themes and plot elements but uses them in a different way. The result is a reinterpretation that will still be partly fresh even for those familiar with the manga.

The biggest change from the manga involves narrowing the focus to Kasumi, rather than splitting it between Kasumi and Marco, which results in the original main villain being reduced to an easy-to-miss cameo appearance and thus turns the label “King of Thorn” into more of a figurative rather than literal interpretation. This is actually an improvement, however, as it eliminates a pedestrian “I want to rule the world and shape it how I see fit” supervillain God complex gimmick in favor of a much more intimately-focused story about the sometimes-unpredictable shape that the pain of traumatic loss can have, especially when volatile forces are involved; this theme was always present in the original material but got submerged under the build-up to the climactic heroic confrontations. Casting the whole story within the framework of Sleeping Beauty – which, surprisingly, was not done at all in the source material even though it's almost a perfect fit – is a distinct improvement, too. Other major changes with more questionable benefits include turning one major supporting character into the installation computer's AI and shifting the revelation that governments were suspicious of Venus Gate (which was the name of the cult in the source material, not the biotech corporation) to the beginning. Amongst more minor changes, mostly ignoring the ability of the patient bracelets to show the progression of Medusa in a subject is a negative, while alterations to who lives and who dies, and under what circumstances they die, are more ambivalent and eliminating certain silly elements (the giant rabbit, for instance) are actually positives. Turning what was originally a videotaped info dump into a story told as the characters move along also is an improvement. A few cosmetic changes – such as one character who tried to commit suicide by slashing her throat in her backstory now slashing her wrist instead – have no significant impact.

The result is a movie every bit as action-packed as its source material, albeit one with a nearly relentless pace. Action junkies will find no shortage of derring-do to keep their interest, whether it be dramatic rescues, hair's-breadth escapes, monster-battling, or negotiating tricky environmental hazards. Those who favor graphic content will also find plenty to like; although the movie does not go to extremes beyond one scene where a character gets forcibly pulled through a door, bloody violence (and characters getting eaten!) is not unusual and one late scene does have some barely-defined nudity. The movie also does a commendable job of firmly-establishing the crucial Kasumi/Shizuku relationship from the beginning, more thoroughly clarifying the known information about Medusa early on, efficiently filtering in essential character development points amongst all of the action content, and dropping vague hints about the ultimate truth behind the thorns and what happened to the world. On the downside, it too rarely pauses to allow major developments and revelations to sink in and does not give enough of a chance for the horror aspect to sufficiently develop. That hinders the movie in achieving a full dramatic impact. It also seems to ignore that one major issue has not been adequately resolved at its end, and given the context it is not an issue that can simply be blown off unless one views the ending in a much grimmer light than it was probably intended.

Sunrise's technical effort on the movie is quite sharp, though not as flawlessly so as one might expect from a feature release by a top studio; occasional slips in fine artistic quality control do pop up, especially early on. Even so, character designs are well-rounded, well-colored, and aesthetically pleasing even when they are not supposed to be handsome or pretty, detail work in the backgrounds is impressive, and 3D modeling in scenery shots is used very well. All of the critters are fully rendered in CG, and they not only look suitably monstrous but also move like living things and interact smoothly with the more conventionally-animated characters; the only minor flaw here is that the thorny vines are, in places, too clearly CG. The animation effort falls only a little short of top-of-the-line, with a wealth of detailed movement even in backgrounds. Enhancing it all are some excellent venues and shot selections.

The musical effort, however, is top-rate. Toshihiko Sahashi, whose varied career as an anime music director includes franchises like Full Metal Panic!, Hunter X Hunter, Mobile Suit Gundam Seed, and Steel Angel Kurumi, turns in one of his career-best efforts here in producing a wonderful score. Anchored by a morose, haunting melody interpreted in many forms by both vocals and instrumentals, it hits all of the right notes to enhance and advance the mood and tension of each scene without ever being oppressive. It also lends to the work a vague fairy-tale-like feel which supports the extensive Sleeping Beauty analogies. Appropriately-titled ending theme “End of the World,” sung by top-selling Japanese recording artist Misia, gives the movie a fitting round-out.

English ADR Director Christopher Bevines chose his cast for the movie very carefully, which results in a nearly flawless casting job and performances that are almost always on-the-mark for both the roles and the original Japanese performances. Brina Palencia's experience in other tragic, emotionally delicate roles (Juliet in Romeo X Juliet, for instance) makes her an ideal fit as Kasumi, while Patrick Seitz (who also wrote the script) makes a proper Marco. The main, readily noticeable difference between the two dubs is that the English one diligently infuses in all sorts of ethnic accents, which turns Marco into a Brit (he was implied but never explicitly stated as an American in the original manga) and the senator into an Italian (likewise). The writing also adjusts for colloquial slang

Funimation's release of the movie included both DVD and Blu-Ray versions in the same case. The Blu-Ray version is unquestionably the way to go if one has the capability, as the artistry is very visibly sharper – to an outstanding degree, even – and the color saturation is distinctly richer on the Blu-Ray; in fact, this may be one of Funimation's best-looking Blu-Rays to date, and it sounds pretty good, too. Extras on both include common fare like assorted advertising trailers but also a few meatier offerings, such as a pilot film which show some interesting differences compared to the finished product: the coloring of outfits and monsters are different and some scenes are shown which never appeared in the movie. Also present is an 11 minute interview with the director and a 29 minute Q&A promo event taped at an Ikebukero theater which features the director and producer. Both offer up some intriguing tidbits, such as the major changes being approved by the original creator, how certain changes were necessitated by narrowing the focus to Kasumi, and how the opening shots of New York City were carefully chosen to promote a thorn motif – something that viewers are unlikely to catch on a first view but which is much more noticeable the second time around if one knows to look for it. There are many other subtleties in the movie which are explained by these features but likely will also go unnoticed without an alert to look for them.

Ultimately King of Thorn has too many imperfections in its writing, pacing, and details to be one of the elite anime movies, but it still stands as both a solid reinterpretation of the original subject matter and a satisfying stand-alone effort.