Twin sisters Ruka and Rumi are the same in every regard. Not just in their appearance and mannerisms; even their performances in school and sports are exact matches. Unfortunately, this also means they both fell in love with the same boy. Handsome track star Touma confessed only to Ruka however, causing a divide between the otherwise-inseparable twins. A divide that would soon lead to tragedy.
Umi no Yami, Tsuki no Kage is 1989 psychological drama OVA with a hearty dash of horror on top. Its story kicks off when Ruka and Rumi take shelter from a storm inside a cave. They find something they shouldn’t have found, which grants the girls strange powers. After this incident, Rumi undergoes a stark transformation. Driven by her envy over Touma, Rumi starts lashing out at people with lethal results. Being the source of her sister’s anger, Ruka realizes that she is going to be targeted as well sooner rather than later.
I was surprised with how well Umi no Yami, Tsuki no Kage nails the thrill of slasher movies. Rumi is violent, unrelenting, and wholly unpredictable. She is constantly working on her next moves, which keeps Ruka (and the audience) always on the back foot. Always feeling like prey before an overpowering predator.
This kind of appeal blends interestingly with the story’s shoujo influences. As the body count piles up and the violence becomes increasingly cruel, you’re constantly reminded that this is all because of a teenage romance. That Rumi is an overemotional girl acting out of jealous rage. Her motivations are shockingly juvenile when contrasted against the actions they inspire her to commit. It feels incomprehensibly human.
Rumi alone made this OVA worth seeking out, but it has many more qualities to offer. Visually its a solid experience with some amazing cuts scattered throughout. Director Satoshi Dezaki did a lot of OVA and movies back in the day, including personal favorites like They Were 11 and Tobira wo Akete. Even in a smaller production like this, his experience and that of his team shine through. Character designer Setsuko Shibuichi also did a wondrous job adapting the look of the characters from manga to anime.
I’ll quit rambling for now. Umi no Yami, Tsuki no Kage earns a stellar recommendation. It’s a fine addition to the wonderful niche of vintage shoujo horror anime.