::'''Shion'''
[[quoteright:225:http://static.tvtropes.org/pmwiki/pub/images/Sion_4169.jpg]]
->Voiced by: YuukiKaji (JP), Creator/GregAyres (EN)

A boy raised among the elite of No. 6, only to be stripped of his privileges after giving shelter to Nezumi, a fugitive. He is unfailingly polite and idealistic and refuses to give up on saving the people of No. 6.
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* {{Adorkable}}: Often.
* AdaptationDyeJob: His eyes were violet in the novels as opposed to the red in the anime and manga.
* [[spoiler: BackFromTheDead]]
* BadassAdorable: He seems all cute and innocent on the outside, but mess with someone he cares about, specifically Nezumi, get ready for the beatdown of your life.
* BewareTheNiceOnes
* {{Bishonen}}: Not nearly on the same level as Nezumi, but he still qualifies.
* BrainyBrunette: Before the Wasp, anyway.
* [[spoiler:BreakTheCutie]]: [[spoiler: Shion, in the Correctional Facility]]
* ChildProdigy
* [[spoiler:[[DidNotGetTheGirl Did Not Get The Guy Or Girl]]: Not only does Nezumi leave him behind when they're done, but Safu, his [[GayOption Het Option]], AscendsToAHigherPlaneOfExistence. However, there might be hope because Shion promises that he'll meet Nezumi again at the end of the anime and novels.]]
* DisappearedDad: Mentioned only in the novels. His mother claims he was careless with money and women and was borderline alcoholic.
** [[spoiler: Beyond gives more information. Also, Nezumi meets him.]]
* DiseaseBleach: The reason for his white hair.
* EvenTheGuysWantHim: Nezumi, of course, but he was also hit on by a greasy old corpse-collector, with promises of drinks and meat, no less.
* FriendToAllLivingThings: He took in the fugitive Nezumi and treated his wound when they were children, dooming his bright future in the process. Years later, [[CuteMachines Nezumi's mice]] take a liking to him (he even gives them names), he reads to the neighbouring kids in the [[WretchedHive Western Block]], he gets along with Dogkeeper and [[AmbiguousGender his/her]] dogs, and Rikiga even calls him an [[TooGoodForThisSinfulEarth "angel"]] at one point.
** And in the end, he [[spoiler: adopts the ridiculously cute baby he saved two episodes earlier.]]
* GeniusDitz : Even though Shion is naive and lacks a sense of self-preservation, he was ranked the highest in the city's intelligence test when he was just two years old.
* HoYay: With Nezumi. Invoked deliberately, and by the end, [[OfficialCouple confirmed]].
** [[spoiler:ChastityCouple]]: [[spoiler: For all the HomoeroticSubtext between the pair, their relationship was not portrayed as overtly sexual, at least in the anime and manga.]]
* LockedIntoStrangeness: After his encounter with [[spoiler:the wasp.]] [[spoiler: Shion after surviving the wasp being born. He also gains a [[GoodScarsEvilScars red snake-like mark curled around his body from his ankle to his neck]]. [[HoYay Not that Nezumi minds.]]]]
* LoveMakesYouCrazy: When Nezumi is threatened, Shion switches from either all-out rage or cold, completely rational and ''murderous.''
* MommasBoy: Well his mom ''is'' Karan. Shion was raised solely by his mother and both of them are very (happily) devoted to one another.
* MoralityPet: For Nezumi. An unusual example in that he struggles with moral issues himself--[[spoiler: in fact, he becomes more willing to hurt others through his association with Nezumi, in a sort of reverse MoralityPet effect.]]
* MeaningfulName: "Shion" is a flower (specifically, a type of aster) with medicinal value. The flower also means "I will remember you" or simply "remembrance" in Japanese tradition, which could allude to [[spoiler:the ending.]]
* NiceGuy
* ThePollyanna
* RedEyesTakeWarning: Averted most of the time. Threaten Nezumi, however, and [[ShmuckBait see what]] [[{{Yandere}} happens.]]
* SpellMyNameWithAnS: Shion/Sion.
* {{Tareme}}
* [[spoiler:[[ViolentlyProtectiveGirlfriend Violently Protective Boyfriend]]: Do NOT insult or endanger Nezumi.]]
* WideEyedIdealist: He's more on the cynical side, but firmly believes that a bright future is attainable.
* {{Yandere}}
** In the novels, [[spoiler: Shion is close to strangling a man because he tried to kill Nezumi. Only when Nezumi tells him to stop he snaps out of it. And then there's his explanation of what he was doing:]]
*** [[spoiler: That man tried to kill you, so he had to receive punishment.]]
** He also violently attacks [[spoiler: Rikiga when the older man makes a pass at Nezumi]] and later [[spoiler: kills a guard point-blank in the head after he shoots and injures Nezumi]].

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::'''Nezumi/Rat'''
[[quoteright:225:http://static.tvtropes.org/pmwiki/pub/images/Nezumi3_9628.jpg]]
->Voiced by: YoshimasaHosoya (JP), KalobMartinez (EN)

A cynical young man with a dark past. He was [[spoiler:saved by Shion when they were younger, only to return the favor years later]]. Due to his experiences in No. 6, he hates most everything about the city and its people, and is perfectly willing to watch it fall.
----
* ABoyAndHisX: With his mice.
* AttractiveBentGender: As his local theatre was swift to notice, Nezumi makes a ''really'' good-looking woman.
* {{Badass}}: He's awesome personified in this world.
* {{Bishonen}}: Pretty enough to be hit on multiple times and [[spoiler: to [[WholesomeCrossdresser play in drag as the beautiful Ophelia]].]]
* CulturedBadass: He knows a lot about literature and is an actor by trade.
* TheCynic
* DarkAndTroubledPast
* DudeLooksLikeALady: He's a talented actor and performs in Shakespearean plays for a living. Shion first sees him playing Ophelia in {{Hamlet}}.
* [[spoiler: EasilyForgiven: Shion was furious when Nezumi admitted that he was using Safu as an excuse to break in the facility for his own agenda. All is forgiven when Nezumi is seriously injured (only a few minutes after the revelation) and Shion rushes to heal him.]]
* EvenTheGuysWantHim: Shion being the main example. There is also [[spoiler: the two mooks who wanted "payment" from him after he kisses the prostitute]], and is also implied by Rikiga [[spoiler: when he offers Nezumi a job as a gigolo]].
* GrayEyes: Occasionally silver.
* HoYay: With Shion. Invoked deliberately, and by the end, [[OfficialCouple confirmed]].
** [[spoiler:ChastityCouple]]: [[spoiler: For all the HomoeroticSubtext between the pair, their relationship was not portrayed as overtly sexual, at least in the anime and manga.]]
* JerkWithAHeartOfGold: He can be a {{jerkass}} at the very least. But he also sings to Dogkeeper's dying pack members to ease their suffering, to say nothing of what he'll do where Shion is concerned.
* OnlyKnownByTheirNickname
* [[spoiler: LastOfHisKind: Nezumi is all that is left of the Forest People that lived on the site where No. 6 was built.]]
* TallDarkAndSnarky: Oh yes.
* [[spoiler: MagicalNativeAmerican: He can "hear" nature, and can sing a song of calming.]]
* [[MeaningfulName Meaningful Nickname]]: "Mouse" or "rat", a name given to him after [[spoiler:escaping the destruction of his homeland and the slaughter of his people.]] His real name is never revealed in-series.
** [[spoiler: He also goes by "Eve" when onstage. Two guesses as to who Adam is...]]
* RealMenWearPink: He's extremely tough and stoic, but also loves reading and singing, and [[WholesomeCrossdresser regularly performs in drag]].
* [[spoiler: ScarsAreForever: The massive burn scars on his back are courtesy of the flamethrower-wielding No. 6 soldiers that slaughtered his people.]]
* {{Tsundere}}: Especially towards Shion. [[spoiler: He'll deliver an angry rant at No. 6, but the moment he sees Shion is upset he gently comforts him.]]
* {{Tsurime}}
* WhatBeautifulEyes: In the novel, Shion almost cannot mention Nezumi without talking about how beautiful his eyes are.
* WholesomeCrossdresser: As part of his acting job. He's very good at it, too.
* YouGottaHaveBlueHair: Blueish, grayish, off-purpleish, depending on your point of view.

--

::'''Safu'''
[[quoteright:225:http://static.tvtropes.org/pmwiki/pub/images/Safu_271.jpg]]
->Voiced by: KiyonoYasuno (JP), Creator/HilaryHaag (EN)

Shion's childhood friend and a fellow resident of No. 6. Like Shion, she's a child genius - her expertise is the human brain and to a degree, psychology. Also like Shion, Safu begins to show doubt about the utopia that is No. 6.
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* AmbiguousDisorder: Often seems lost in social situations, such as [[DoYouWantToCopulate her proposal]] to Shion or cluelessness about romance when studying abroad. However, her behavior may just be a result of growing up as a sheltered child prodigy.
* [[spoiler: AscendedToAHigherPlaneOfExistence: She becomes a physical medium for Elyurias.]]
* AdaptationExpansion: She is given a much larger focus in the Anime than in the original novels.
* BerserkButton: Go ahead, interrupt her presentation on the human mind or insult her grandmother.
* BrainyBrunette
* ChildProdigy
* DamselInDistress: [[spoiler: After being captured by the Bureau of Public Security. Turns into a DamselOutOfDistress when she uses Elyurias' power to help Nezumi and Shion by controlling the Correction Facility's computers, although her role consists less of kicking ass and more of standing around and looking kinda creepy.]]
* [[spoiler: HeroicSacrifice: When Nezumi and Shion blow up [[MasterComputer Mother]], she stays behind with Elyurias in order to destroy it for good]].
* [[spoiler: IncompatibleOrientation: The fate of her affections toward Shion.]]
* IWantMyBelovedToBeHappy: Tells Shion she's fine with him having a girlfriend while she's gone [[spoiler: and brings him BackFromTheDead while possessed by Elyurias before [[AscendToAHigherPlaneOfExistence Ascending to a Higher Plane of Existence]]]]
* NoSocialSkills: She functions well in No. 6, however she's seen as odd by her peers when she studies in No. 5. It certainly doesn't help that her request to Shion before she leaves to study abroad is "I want to have your sperm."
* SweaterGirl
* UnluckyChildhoodFriend: Shion flat-out states in the novels that while he treasures her as a friend, he does not and cannot return her romantic feelings. Aside from Shion's [[HoYay attachment to Nezumi]], circumstances just do not work in her favor.

--

::'''Inukashi'''
[[quoteright:225:http://static.tvtropes.org/pmwiki/pub/images/Inukashi_6415.jpg]]
->Voiced by: KeiShindou (JP), Creator/LuciChristian (EN)

One of the residents of the West Block outside of No. 6. Inukashi, quite literally "Dog Keeper," is a brash, often dangerous individual who spends his (or her) time either renting out his many dogs as heaters during the winter or collecting items to sell from an illicit contact within No. 6's correctional facility. He has a very violent, volatile relationship with Nezumi, but Nezumi still often goes to him to gather information - for a price.
----
* AmbiguousGender: ''Assumed'' by some to be female, based on his small stature, nice legs, and one mention of 'softness' when he was hugged, however official information does not give a definite answer one way or another.
** SamusIsAGirl: Treated by the other characters as male, until used as bait to lure in a No. 6 higher-up: Shion, trying to comfort Inukashi afterward, wonders if his friend might actually be a girl. The rescued baby from episode 10 also calls Inukashi "mama". Even so, Inukashi never personally discusses his gender identity, so there's no way to know.
* CrossdressingVoices: [[AmbiguousGender Sort of]].
* BerserkButton: Inukashi does not react well when his dogs, especially his 'mother', are insulted.
* MeaningfulName / OnlyKnownByTheirNickname: [[EveryoneCallsHimBarkeep Inukashi literally means Dog-keeper, or Dog-loaner.]]
* [[RaisedByWolves Raised By Dogs]]: His "mother" was a dog that offered milk and kept him safe.
* {{Tsundere}}: Only towards Shion.

--

::'''Karan'''
[[quoteright:225:http://static.tvtropes.org/pmwiki/pub/images/Karan_6372.jpg]]
->Voiced by: Creator/ReiSakuma (JP), LesleyPederson (EN)

Shion's mother. With Shion, she was sent to live down in Lost Town where she opened up a bakery. She and Nezumi contact one another through strips of paper brought by mice.
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* [[ChickMagnet Dude Magnet]]: She has a lot of admirers...
* FriendToAllChildren: Thinks children are adorable, and strongly believes it is an adult's responsibility to protect them.
* [[GoodParents Good Parent]]: She really loves Shion and isn't upset at all about their downgrade from a life of luxury.
* MysteriousPast: At least one photo of her exists with the Founding Members of No.6. She also knew where Rikiga was likely to be in the West Block.

--

:: '''Rikiga'''
[[quoteright:225:http://static.tvtropes.org/pmwiki/pub/images/Rikiga_80.jpg]]
->Voiced by: MasakiTerasoma (JP), ChrisHutchison (EN)

One of the residents of West Block. He runs a prostitution service which allows him a life of luxury in comparison to other residents. At one point, he wrote articles regarding No. 6.
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* CowardlyLion: He really ''doesn't'' want to get involved in Shion and Nezumi's plans, but does so anyway.
* [[{{Fangirl}} Fanboy]]: He really likes Eve, Nezumi's stage persona. He's less charitable towards Nezumi, given that well, it's [[{{Jerkass}} Nezumi]].
* IntrepidReporter: Hinted that the reason he was sent to live in West Block was due to his articles questioning No. 6's activities.
* ParentalSubstitute: He ''tries'' to be this to Shion from time to time, given that he's still attached to Karan.

--

:: '''Yoming'''
->Voiced by: Creator/ShinichiroMiki (JP), KarlGlusman (EN)

One of the residents of No. 6, and a resistance fighter. Yoming first begins to suspect something is amiss in the city when his wife and child mysteriously disappear. He takes interest in Karan after Shion's disappearance.
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* ConspiracyTheorist: Luckily (or unluckily), the conspiracy is ''real''.
* [[spoiler:KarmicDeath: Though starting out with the intention of avenging his family's death, he eventually descends into creepy and unwanted advances on Karan and gleefully planning to incite a mob bloodbath on No. 6's founding anniversary. He ends as another victim of the birth of the wasp.]]

--

:: '''Elyurias'''
->Voiced by: MaoDaichi (JP), GenevieveSimmons (EN)

A mysterious entity, subject to much research by the scientists of No. 6. [[spoiler:Elyurias once existed in the forest that was destroyed by No.6's operatives, and has power over nature. She was worshiped by the Forest People as a god. No. 6's government has gone to great lengths to research how to control her power.]]
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* BlueAndOrangeMorality
* EverythingsWorseWithBees: Elyurias occasionally appears as a giant one.
* [[spoiler:GaiasVengeance: Unleashes this on the city during the ending.]]
* [[spoiler:FaceFullOfAlienWingWong: Elyurias reproduces by laying eggs in the bodies of other species. Namely, humans. The process of a bee being born causes the host to rot away very, very quickly.]]
* MotherNature
* NatureSpirit
* [[spoiler:SymbioticPossession: Though forcibly implanted into Safu, they do not seem to bear each other ill will.]]