!!Kazuki Yotsuga
!!!Voice Actors: Takayuki Yamaguchi (Japanese), Jeremiah Freedman (English)
The main hero and Core Robot pilot, an OrdinaryHighSchoolStudent who's sent to a parallel world where giant robots fight each other, and ends up surrounded by women.

* AcePilot: Often called a "natural".
* BadLiar
* BewareTheNiceOnes: He rarely gets ''really'' angry, but when he does...
* {{Expy}}: Of Shinji Ikari from ''Anime/NeonGenesisEvangelion'', though only in appearance.
* NiceGuy
* OrdinaryHighSchoolStudent
* StoryBreakerPower: Not only can [[spoiler:Zimv]] create black holes, he also has the ability to ''grow'' [[InfinityPlusOneSword Light Hawk Wings]].
* [[StrongAsTheyNeedToBe Strong as He Needs to Be]]
* TookALevelInBadass: Started piloting the robot he'd nicknamed "Hartzenen". He later ''upgrades'' to the SuperRobot [[spoiler:Zimv]].
* UnluckyEverydude
* UnwantedHarem

!!Mitsuki Sanada
!!!Voice Actors: Creator/RieTanaka (Japanese), Creator/MichelleRuff (English, as "Georgette Rose")
Mitsuki is the popular girl, and daughter of [[MadScientist Dr. Ken Sanada]]. She lures Kazuki to her house for her father's experiments, but is sent to the parallel world along with him.

* AlphaBitch
* BrainwashedAndCrazy: Near the end of the series, temporarily.
* CannotSpitItOut: She has a hard time admitting her feelings for Kazuki to herself, let alone telling him.
* ClingyJealousGirl: She hates it when Kazuki gives the other girls attention, Yayoi and Mitsuki Rara ''always'' bring out the worst in her.
* DamselInDistress: She was kidnapped by the Rara Army.
* DefrostingTheIceQueen: When [[spoiler:the pair return to their own world]], she starts to defrost a little towards Kazuki and just hangs out with him like they're friends.
* DudeMagnet: Very popular and young men constantly send her gifts and cards.
* {{Expy}}: Of Asuka Langley Soryu from ''Anime/NeonGenesisEvangelion''.
* HairDecorations
* JerkWithAHeartOfGold
* MadScientistsBeautifulDaughter
* RapunzelHair
* SchoolIdol: The most admired girl in Kazuki's school.
* SpoiledBrat: Though she's not ''that'' bad.
* TeamChef
* {{Tsundere}}

!!!Voice Actors: Creator/AiUchikawa (Japanese), [[Creator/SherryLynn Katie Ashley]] (English)
D is a bioroid, an artificially constructed being. The war between the Earth Defense Force and the Rara Army began when D and at least two mechas were discovered in an alien artifact. [[spoiler:She finally returned to her original body in the second-to-last episode]].

* ArtificialHuman: Called a Bioroid.
* BadDreams: [[spoiler:Most likely caused by Himiko]].
* BewareTheNiceOnes: As Ayuko and [[spoiler:Kumu]] find out the hard way.
* BewareTheQuietOnes
* CreepyChild
* CuteBruiser
* DreamingOfThingsToCome: See: BadDreams above.
* EmotionlessGirl
* ExoticEyeDesigns: Has a circle parallel to the iris.
* HairDecorations: Her headband.
* NoSocialSkills: To the point where she had no idea what to do with a basket of wet laundry (while standing in front of a clothesline).
* OneLetterName
* OOCIsSeriousBusiness: It is actually noted by Mitsuki and Dr. Ken Sanada when D introduces herself to Kazuki after he greets her for the first time, as they find it surprising.
* PeekABangs: Her hair covers her left eye. It also covers up a glowing orb in one of her eye sockets. Some suspect it's her soul, but they are not sure.
* PurpleEyes
* TheQuietOne: She says very little, and almost never initiates a conversation with anybody.
* ReiAyanamiExpy: Quiet and seemingly emotionless HumongousMecha pilot with NoSocialSkills who is also an ArtificialHuman with unusual eye and hair color and pale skin. For bonus points, the other main characters are expies of Shinji and Asuka.
* SugarAndIcePersonality
* YouGottaHaveBlueHair: ''Bright'' green hair.

!!Yayoi Schwael
!!!Voice Actors: Creator/ChieNakamura (Japanese)
Former pilot of "Hartzenen" (the white robot) but had the misfortune of being injured and losing that ability. Kazuki saved her life and she fell [[RescueRomance head over heels in love with him]].

* ActionGirl: Even though she can't pilot a robot anymore, she should ''not'' be underestimated.
* ClingyJealousGirl: Has some traits of this.
* FairCop
* RescueRomance
* {{Tsundere}}

!!Mitsuki Rara
!!!Voice Actors: Creator/MegumiToyoguchi (Japanese), Creator/WendeeLee (English)
Originally known as "Miss Ra", the Rara Army's spokeswoman and mascot, it's later revealed that she's Mitsuki Sanada's counterpart in the parallel world.

* AlternateSelf: She's Mitsuki Sanada’s counterpart in the parallel world. They look exactly alike except for the color and style of their hair.
* HeavySleeper
* InnocentFanserviceGirl
* NiceGirl: The genuinely kindest character other than Kazuki.
* {{Sleepwalking}}

!!Ken Sanada
!!!Voice Actors: Ryūsuke Ōbayashi (Japanese), Creator/KirkThornton (English)

* CloudCuckoolander: [[ObfuscatingStupidity Or is he?]]
* MadScientist
* OmnidisciplinaryScientist


!!Ayuko Rara
!!!Voice Actors: MikaDoi (Japanese), Diva West (English)

* AbusiveParents: To Mitsuki
* AxCrazy
* BigBad: Of the second half of the series.
* CardCarryingVillain: Acts like one.
* [[DimensionLord Dimension Queen]]: She'd certainly like to think of herself as such.
* SmugSnake
* TheTrickster

!!Hiroshi Rara
!!!Voice Actors: KenichiOgata (Japanese), G. Gordon Baer (English)
* AntiVillain
* BigBad: Until [[spoiler:Ayuko takes over]].