Tatsuya Tsugawa's parents die in an accident. One week after the accident, he has inherited millions of yen and is now starting high school. He now tries to follow his father's last words about being a man of high caliber. A little while later, Tatsuya tries to rescue a girl, Seine Miyazaki, from being bullied. She coldly rebuffs his attempt and claims that she likes being bullied. He still tries to help her despite the fact she told him to leave her alone. It turns out that Seine is immortal, and she kills parasitic bugs that control humans with a snake named Aion that devours them.Hekikai no AiON is a fantasy and horror manga by Yuna Kagesaki, known for Karin and Oniichan Control. The series is currently being translated by Tokyo Pop under the name Aion.Not to be confused with the game Aion.
Tropes this series provide are:
Adventures In Comaland: Tatsuya went into Seine's induced dream in order to wake her up.
Affably Evil: Ariel, the eldest of the mermaid sisters, is less of a Jerkass than the rest of her sisters and she genuinely cares about Sheila maybe because she ate Shimon's heart...
Then played with; Shrinking Violet but exotic mermaid and human but Broken Bird witch. Though Tatsuya shows more attraction to Seine, he still can leave Sheila alone when she's in trouble...
Big Fancy House: Tatsuya and Seine live in one of this. Later, Shizuki and Yuzuki join in. Then, in the Time Skip, the ones who join in are Tsukasa and Minagi
Bishounen: 19-years-old Tatsuya. Minato also counts, with or without Time Skip
Bloodless Carnage: Averted. When Seine is killed, she bleeds as any normal person would do.
Fanservice with a Smile: Played for Laughs, since all the boys dress in Meido costumes. Tatsuya gets more focus since his skirt is too short because of him growing, and his weeping, red face.
First Name Basis: When Tatsuya at first started calling Seine by her last name. After they started living together, She tells him to call her by her first name since she thinks Miyazaki is "made up". Also, Seine just calls him Tatsuya.
Innocent Fanservice Girl: Seine, being an Emotionless Girl who consideres herself as a monster, is not bothered if somebody sees her shirtless or grabs her chest and she even takes her clothes up once to show Tatsuya that her wounds are healed. Of course, even if she doesn't freak out, Tatsuya does.
Sheila counts too, being a mermaid, she is shirtless all the time; every time she sees Tatsuya after getting her human form, she's naked and of course Tatsuya gives her the classic Please Put Some Clothes On scream.
Pretty Freeloaders: Seine, Shizuki and Yuzuki (for a while) and, after Time Skip, Sheila. Tatsuya, apparently, has a thing for picking up girls to live in his house.
Rule of Three: Seine can die just three time per day. If she dies more than that, Aion has to "recharge" itself and Seine will feel the pain of all those deaths before she can use Aion again.
Pet the Dog: Seine comfort Tatsuya in the first chapter saying him he can become a high caliber man
Shipper on Deck: Minagi seem to like shipping Seine with Tatsuya. It helps that it's obvious the guy is really in love with the girl and she wants to help him.
Your Approval Fills Me with Shame: Seine got no other option but rip the Mushis out of a crowd of brainwashed and crazy students without excite the Mushis first. Shizuki applause this act. Seine was not amused since she know what doing that means.