Hikaru Takabe may not be the most social of teens. Always sporting her headphones, she gives off an aloof aura that rubs her classmates the wrong way. But her not being part of the crowd takes on a different dimension when she becomes involved in an intergalactic game of cat and mouse.

Inspired by ''Needle'', the Golden Age hard sci-fi classic by the late Creator/HalClement, Nobuaki Tadano's debut work brings a unique take on alien invasion up to date and into the maelstrom that is the Japanese high school girl.


* AlienInvasion: The alien Maelstrom takes a host and then goes on a killing spree. Horizon follows him an attempt to stop him. [[spoiler:Repeat ad infinitum.]]
* ApocalypseHow: According to Horizon, Maelstrom is trying to bring about a Universal Class 4 (and it's implied that he ''already'' did this to Earth once, per the extinction of the dinosaurs). [[spoiler:Later on, the Moderator plans to initiate a Planetary Class 4, by pushing the ResetButton on evolution and returning all life on Earth to primordial ooze.]]
* BodyHorror: Oh, ''yes''. Expect things to get messy whenever Maelstrom is around. And it gets even worse later.
* ButNowIMustGo: [[spoiler:Horizon and Maelstrom leave the Earth in the end, albeit having come to terms with each other.]]
* {{Gorn}}: Again, '''''yes'''''. To put it into perspective, we see Hikaru (the '''main character''') get vaporized layer-by-layer at the beginning of the ''very first chapter''. And that's just the beginning...
* DefeatMeansFriendship: [[spoiler:Maelstrom, surprisingly.]] And again, later on with Chika.
* HeelFaceTurn: [[spoiler:Maelstrom.]]
* HeadphonesEqualIsolation: Hikaru. [[spoiler:She abandons them after her CharacterDevelopment.]] In the epilogue, she runs into a boy who seems to embody this as well. [[spoiler:He even appears to be "talking to himself" in the same way that Hikaru did with Horizon.]]
* IJustWantToHaveFriends: Chika wants to find companions who won't judge her so harshly.
* KidsAreCruel: When Shunsuke's class has to dissect frogs, the other students in his group know good and well that he shouldn't be around sharp objects, but they do nothing about it. And then he suffers a nervous breakdown that allows Maelstrom to take over his body. [[NiceJobBreakingItHero Nice Job Breaking It, Students]].
* {{Kuudere}}: Hikaru.
* LovecraftianSuperpower: Hikaru's symbiosis with Horizon borders on this, but the trope really comes into play when [[spoiler:Horizon manages to take Maelstrom prisoner... inside of Hikaru.]]
* NiceJobBreakingItHero: [[spoiler:Horizon manages to find a way to permanently end Maelstrom's extinction spree by containing him within himself (and, by extension, Hikaru). Unfortunately, Horizon and Maelstrom's little cat and mouse game existed to keep the evolution and mutation of life in check, and now that they've both "abandoned their positions"...]]
* OrdinaryHighSchoolStudent: Hikaru, until she ended up sharing her body with a super-powered alien.
* ThePowerOfFriendship / ThePowerOfLove: Or, as Horizon calls it, the "heart bonds of lifeforms" are what save Hikaru from Maelstrom's nightmare world.
* SecretKeeper: Saya, though she doesn't know exactly what's up with Hikaru, knows that she's involved with some sort of craziness. Nao gets in on some of it later on.
* TearfulSmile: Hikaru, near the end of the second book. [[WhenSheSmiles It is beautiful.]]
* ViciousCycle: Maelstrom attempts to wipe out all life on a planet, Horizon chases him and attempts to stop him. They move onto another planet, Maelstrom wipes out all life, Horizon chases him, they move onto another planet...
* WakeUpGoToSchoolSaveTheWorld: This is basically Hikaru's life after Horizon shows up. The "Save the World" part goes a little slowly until Maelstrom finally makes himself known.
* YouAreNotAlone: Said to Hikaru several times. It slowly becomes true of her as the story progresses and she opens up to other people. [[spoiler:While outright not said, she pulls a similar ploy on Chika in the climax.]]