MiddlingTaste’s review published on Letterboxd:
Now that's a good one-shot OVA!
This was really solid. I appreciate how the plot draws from a few different "flavors" of horror to craft a story that, while not as indelibly horrifying or visceral as certain examples of the genre, ends up being eerie and haunting in a way that quietly gets under your skin. You've got some body horror (of both the gushing blood and grody monsters varieties), a healthy dose of psychological horror (with a strong existential streak), some great Gothic imagery (the spooky, ethereal shots of Misa lying in the middle of the moonlight-bathed floor in a pool of blood are going to stick with me for some time), and the quietly mythic terror of a folkloric ghost story. The atmosphere and presentation are quite sharp too, with lots of great mood-setting lighting and a beautiful violin score that grants the OVA an elegiac quality.
There is some context and background from the greater storyline of the Mermaid Saga manga that would be nice for newcomers that isn't really included (I made sure to brush up on the canon beforehand because I had heard this was the case). That said, the only aspect of that that really matters for this particular chapter of the story is what pertains to the protags Yuta and Mana, and that's sketched out well enough that you don't need all the details to catch on.
Overall, a really neat, creepy little horror OVA! I wish Shogakukan or Rumiko Takahashi or whoever is responsible for its current unavailability would let it come back into print. The animation and presentation on this is good enough that I'd imagine it could look really good with an HD remaster, assuming the original film elements are still around.