Manga Review - Hekikai no Aion - A Decent Plot but Underwhelming Development

Mythical Asian creatures and monsters have always been an interesting aspect of "fictional" tellings. When I was young, I was watching a scary movie with my cousin involving Chinese Vampires or rather Jiang Shi. Since watching anime and Japanese horror movies, Japanese mythical creatures/monsters have always been fascinating. Hekikai no Aion takes on the illusive mermaids who infect humans with mushi, giving them control of the human's actions. When there is an enemy, there must also be a "hero"/"ally", and the main protagonist has a vendetta against the mermaids, who killed her mentor. Hekikai no Aion has a decent plot, but I felt that there could have been more development of the story.

Story (7/10):

If you like Mushishi, but more action orientated, this is probably for you. I stumbled upon this manga when I was searching for "Horror" Manga. Unfortunately, there's no horror aspect to this. What I liked about this manga was its approach to resolve issues. By the end of the manga, all complications were resolved, and there were no questions left to answer. 

However, this was let down by its underwhelming development of the story. I felt that some parts of the story could have been a bit longer or elaborated more. One example is how you can kill Seine, who is immortal. She essentially unleashes her power when she "dies", so I don't see how the mermaids can ever kill her (unless the author is telling me that the mermaids have to consume her). I also felt that the revelation of why the main antagonist (the Big Sister Mermaid - forgot her name) is not so scary, was a bit dissatisfying. The author justifies that the mermaid is controlled by Seine's mentor since she consumed Seine's mentor's body. However, I didn't really mind it, and it somewhat made sense, because Sheila somewhat resembled Tatsuya's mother.

Characters (6/10):

The characters are not particularly interesting, but they act like their age. The two main protagonists occasionally act like antsy teenagers, which is characteristic of their age. Sheila was a good character that was used to facilitate a romantic tension between the two protagonists. Other than that, the other characters wasn't really that much interesting.

Art (6/10):

The art wasn't a strong trait of this manga. However, the art wasn't ugly. It's just that it's plain.

Enjoyment (6/10):

I didn't enjoy this manga as much as I wanted to. First of all, I was disappointed that this is classified as a horror manga. It is clearly not a horror manga. Second of all, I felt that the story had a poor development of the story. I took a long time to read this manga and this was perhaps I was bored of it. I eventually finished it because I like to see things through.

Overall (6/10 or 7/10):

Unfortunately I would not recommend this manga to anyone. Not to people searching for "horror" manga, not for people who like mangas about mystical creatures (like Mushishi), and certaintly not people who like a manga with good plot progression. However, I must commend the author's approach to concluding the story - there was no open-ended ending (perhaps debatable) and no questions/complications left unsolved. Nevertheless, Hekikai no Aion was a disappointing read, and I feel that it's not worth one's time to read.