Umi no Yami, Tsuki no Kage

“Umi no Yami, Tsuki no Kage” is a shoujo horror that has an intriguing premise, but unfortunately the execution is lacking.

This 3-episode OVA based on the manga of the same name centers on twin sisters Ruka and Rumi who both have a crush on the same guy named Katsuyuki. The twins get infected with a mysterious substance from an old burial site that imbues them with powerful psychic abilities whose strength seems to be tied to moon cycles. The infection also causes Rumi to undergo a dramatic personality change, and she becomes ruthless in attempts to kill Ruka so she can have Katsuyuki for herself. ... Meanwhile, Katsuyuki has confessed his love for Ruka, and is adamant that he wants to be with her and not Rumi. As Rumi infects just about everyone around them and turns them in to virtual zombies bent on capturing Katsuyuki and killing Ruka, can the two protagonists escape her wrath?

The beginning of the OVA is promising, but the plot starts to derail quickly as it rides on the protagonists making mind-bogglingly stupid decisions to progress. For instance, after Ruka finds out that her sister killed a classmate, and her sister just attempted to murder her, she acts like it’s a minor inconvenience. She keeps going to school (that her sister also attends) and living at home (where her sister also lives) like everything’s normal. And her would-be boyfriend encourages her to do this. This kind of thing happens repeatedly, to predictable results. They also try to bring Rumi to the doctor so the sisters can be examined, and the doctor proclaims that they’re infected with a bacteria “that may be a virus.” In addition, there’s talk comparing what happened to them to Tutankhamen’s curse, etc. There are inconsistencies in the writing at some points as well.

As this OVA is basically made for fans of the manga, it’s incomplete, and ends abruptly. There’s no conclusion, and the characters are barely developed, if at all.

Speaking of the characters, Ruka doesn’t have much of a personality; she’s just super gullible and weak. Rumi’s personality is essentially that she’s evil and jealous of her sister. Katsuyuki is really pushy in is insistence on pursuing a relationship with Ruka, to the point that he forces himself on her a couple of times. All other characters are one-dimensional, if even that.

As far as technical aspects go, the animation is serviceable, but it’s not that good. The character designs are okay, but not distinctive; they look like the kind of designs you'd find in any other shoujo work. There are some good voice actors in this OVA, but their performances are just average. The ending is just a slideshow of manga images set to a cheap-sounding instrumental track that doesn’t really fit the series. The opening is another generic instrumental piece, and the background music is bland.

Regarding objectionable content, there are several graphic and bloody murders, and a couple of attempted rape scenes. There’s also a little bit of stylized nudity during the opening sequence.

Overall, in addition to poor technical aspects, “Umi no Yami, Tsuki no Kage” is filled with lots of dumb decisions, bad dialogue, inconsistent writing, characters not acting realistically, and an abrupt ending. While the premise is promising, it’s explored poorly here, and there are anime that do what this OVA was trying to do much better (see the recommendations). I wouldn’t recommend watching this unless you’re absolutely starved for shoujo horror content, or you’re a fan of the original manga.

This is one of those OVA’s that leaves me asking for more. It’s almost perfect in everyway and I’m not exaggerating. Many 80’s OVA’s range from mediocre to boring, this is definitely one of the diamonds in the rough.

REVIEW OF PLOT: The makers did the best they could’ve done in 3 episodes. Basically summarizing the first 3 volumes of the manga. The story is a simple concept that’s easy to get into. It takes inspiration of Tutankhamun where a bunch of girls find a grave site in a cave unleashing an ancient type of bacteria that infects our two main characters, twin sisters, Rumi and ... Ruka. Both are infected in different ways which shapes the plot and love interest.
Rumi and Ruka find themselves in a love triangle with a Katsuyuki who is basically, your shoujo anime knight in shining armor. Both of them as infatuated with him. Early on it is discovered that Katsuyuki chose Ruka over Rumi, at the time Rumi “handed” over her crush to Ruka but after the discovery of the gravesite that all changes.
Throughout the 3 episodes it’s discovered the extent of how Rumi and Ruka have been infected, Ruka at first doesn’t notice any difference but Rumi is nearly unrecognizable in terms of personality. Rumi goes from a sweet supportive twin, to a jealous homicidal maniac that will literally do anything to get with Katsuyuki even if it involves killing multiple people in the process. Other than Rumi’s personality she also discovers he has new powers she can use to get to Katsuyuki.
A lot of the anime has Ruka and Katsuyuki on the run from the evil Rumi which always creates a lot of tension, and strengthens their love for each other. It’s done exceptionally well in this OVA. Unfortunately since that this is only 3 episodes we don’t get to see their full romance because both of the love interests compliment each other perfectly. Now I should explain the characters.
Ruka may strike some people as a stupid protagonist, but she is going through the stages of disbelief. She is extremely trusting of her older sister and hasn’t come to terms that Rumi is now a mass murderer that wants nothing more than to kill her own sister. Throughout her life she’s always been in Rumi’s shadow, but desperately wants to be more confident. The turning point in her and Rumi’s relationship is when Katsuyuki shockingly picked her over Rumi.
Katsuyuki is a very likeable guy and definitely isn’t your typical dense anime guy, in fact he’s quite forward and confident which makes his chemistry with Ruka very good.
To explain Rumi, she’s crazy and lusts over Katsuyuki to a disturbing degree. Definitely the perfect villain to this love triangle.
REVIEW OF PRESENTATION: This is peak 80’s shoujo anime. The visuals are very well done, characters look good and are a decent upgrade from the manga. The only thing I would nitpick is the lack of an opening and ending. It’s just stills from the manga. I would’ve preferred a nice 80’s song to go along with it.

Overall, Umi no Yami, Tsuki No Kage is an underrated and unappreciated gem. It leaves me screaming for more. The fact that only 3 of the 18 volumes of this wonderful series got turned into an anime is a complete injustice. For what they were able to accomplish in 3 volumes is incredible and it drew me in right away. Because of this OVA I bought all the volumes of the manga. I highly recommend this to everyone and I try to show as many people I can this wonderful OVA.