Kiyoteru Hiyama
Voiced by: Maruxshadow02
The protagonist of the series, a robotics engineer dealing with the loss of his son.- Big Good: As opposed to Toshiro, he's a genuinely good guy who truly cares about his creations.
- Deadpan Snarker: Can be pretty snarky sometimes, especially when confronted by Toshiro.
- Fatherly Scientist: To his creations, natch.
- Gadgeteer Genius: As an expert on robotics, he definitely qualifies.
- In-Series Nickname: People who know him personally call him "Kiyo".
- Must Have Caffeine: When working all night to fix Miku.Meiko: Did you two sleep at all?
Kiyoteru: WHO NEEDS SLEEP WHEN YOU CAN COFFEE! - Nice Guy: A goodhearted man whose main goal is to support and help his family.
- Only Sane Man: Sometimes, in fact most of the time. However, Meiko shares this role with him later.
- The Smart Guy: A robotics genius.
- Stoic Spectacles: Befitting a robotics genius.
- Team Dad: To the Vocaloid "family". Helps that he was already a dad to begin with. Miku and Kaito especially see him as their dad.
Kaito Shion
Voiced by: TundraZer0, RawrKittyBackup (as a kid), Fanofstarwars22221 (when berserk)
The other protagonist, a robot with the brainwaves of Kiyoteru's son uploaded into him.- Ax-Crazy: One of Toshiro's...secret upgrades to him gave him a split personality that literally tries to murder Len over a video game.
- Back from the Dead: Through Brain Uploading.
- Catchphrase: "DAAAAAAAD!" to the point that there's a compilation video of how much he says it.
- Celibate Hero: So far doesn't show any attraction to anyone. Probably because he was at the "girls have cooties" age when he died.
- Everybody Hates Mathematics: When Kiyoteru tries to test out of Kaito really has actual cognitive abilities as a robot.Kiyo: This calls for math!
Kaito: (long groan) NO DAD! NOOO! - Keet: Having an eight-year-old's brain helps.
- Manchild: Justified as he has an eight year old Kaito's brainwaves in him but looks like an adult.
- Nice Guy: Most of the time, he's pretty friendly.
- Split Personality: Toshiro gives him a very unpleasant one.
- Trademark Favorite Food: Ice cream!
Meiko Sakine
Voiced by: xUNC00Lx
The first robot Kiyoteru created.- And I Must Scream: Toshiro orders her to keep quiet about his "upgrade" to Kaito and she's left with no option but to obey due to her less advanced programming. It's clear that this wasn't a fun experience for her.
- The Conscience: For Kiyoteru, seeing as she repeatedly tries to inform him that she doesn't see Toshiro as a trustworthy individual.
- Deadpan Snarker: Post-upgrade, she becomes a lot snarkier, even jokingly flirting with Kiyo at one point when he reminds her that she's based on his wife.
- Machine Monotone: Before Kiyo gave her an upgrade.
- Tap on the Head: Suffers a severe blow to the head after saving the twins from a falling ladder. The injury she sustains is so severe that it necessitates a full body upgrade.
- Team Mom: Post-upgrade, she becomes more nurturing and maternal.
Miku Hatsune
Voiced by: PrincessDevin302
The third robot Kiyoteru creates, later becoming a virtual idol.- Ax-Crazy: Whatever Toshiro did to her made her into this.
- Cloudcuckoolander: She has her moments.
- Corrupt the Cutie: Whatever the heck Toshiro did to her caused this.
- Daddy's Girl: Quickly becomes this towards Kiyoteru.
- Girlish Pigtails: Something Toshiro demanded and Rin mocks her for.
- G-Rated Drug: She really loves leeks!
- Idol Singer: What she soon becomes.
- In-Series Nickname: Rin mockingly calls her "Pigtails".
- Nice Girl: A friendly, energetic young woman.
- Trademark Favorite Food: Gains a massive obsession with leeks after eating one.
- Unusual Euphemism: "Don't let [Toshiro] steal my flower!"
Rin Kagamine
Voiced by: MewDezziMew (Episode 6) Nikki-Chan (Episode 7 onward)
The fourth robot created by Kiyoteru, a small, bratty young woman.- Art Evolution: Received a higher quality MMD model between seasons one and two.
- Bratty Half-Pint: Especially towards Kaito and Miku.
- Genki Girl: A very loud one at that!
- Jerk with a Heart of Gold: Genuinely cares for her family, despite being a total brat. Especially shown when she expresses concern for Miku after she nearly dies.
- Kick the Dog: In her first appearance, Kiyo and Kaito get into an argument in front of her which ends with Kiyo accidentally shouting at Kaito that he's not really his son and Kaito storming out. Rin's response? To mock Kiyo for it. To his face.
- The Ojou: Of the bratty variety.
- Tiny Tyrannical Girl: To pretty much everyone, especially Kaito, Miku and Len.
- The Trickster: She pretends to be a sweet little girl, just like Miku, during her initial creation. When Kaito makes it clear that he doesn't like her, Rin drops the facade and starts mocking him with an evil little smirk on her face.
- Was It All a Lie?: Worries that Kiyo doesn't really love them and just wants them to make him rich.
Len Kagamine
Voiced by: JCWarriorCats
The fifth and so far last robot made by Kiyoteru, a male counterpart to Rin who isn't very bright.- Art Evolution: Received a higher quality MMD model between seasons one and two.
- Butt-Monkey: He spends an entire scene with a fork stuck in his hand for one thing.
- Cloudcuckoolander: Coupled with his status as a ditz.
- Deadpan Snarker: Sometimes.
- Dumb Blonde: Apparently, due to his creation being rushed.
- Establishing Character Moment: "WHAT'S UP MAH HOMIES!" Rin's response says what we're all thinking.Rin: Oh no, he's an idiot.
- Extreme Doormat: To Rin. She even uses him as a chair at one point.
- Hidden Depths: He's surprisingly observant when it comes to Kiyoteru's relationship with the family. When Meiko claims that Kiyo favors Kaito, Len quickly points out that this isn't true, as when Kaito objected to Len calling the top bunk in their room, Kiyo defended Len over Kaito, which he wouldn't have done if he favored the latter.
- Nice Guy: Nicer than Rin, at least.
- Opposite-Sex Clone: Of Rin.
Toshiro Yamada
Voiced by: PieAnimeOtaku
Kiyo's new employer and implicitly the series' antagonist.- Bad Boss: Pushes Kiyoteru around, pervs on Miku, mocks Yuki and calls her "a housewife in training", yeah, he's a pretty big jerk to most of the people who work for him.
- Big Bad: Shaping up to be the series' main villain. So far, every bad thing that has happened after the timeskip has been his doing, including corrupting both Kaito and Miku and forcing Meiko to keep quiet about the former.
- Corrupt Corporate Executive: Rin's fears about Kiyoteru just wanting them for money is more accurate if applied to Toshiro.
- Even Evil Has Standards: For all his sliminess, misogyny and lechery, he seems genuinely offended when Miku thinks he's trying to rape her. While he claims that it's more because she's a robot, it's worth noting that there's no implication that he'd try anything...unsavory with other girls (for example, Yuki), so he may have actually meant it.
- Evil Laugh: Lets out one while holding Miku captive, something Yuki is quick to mock.Yuki: You call that an evil laugh?
Toshiro: Shut up, I'm working on it! - Faux Affably Evil: Plays himself up as a helpful employer to Kiyo, but Meiko, Miku and Rin all know the truth.
- Handsome Lech: To the point that Miku thinks he's a rapist.
- Hate Sink: He's a corrupt, greedy, perverted, misogynistic scumbag who causes pretty much all of the problems in the series so far.
- Jerk with a Heart of Jerk: He's a tactless pervert, but it seems he genuinely has Kiyo's best interests at heart...and then he corrupts the guy's son.
- Lovable Sex Maniac: The "lovable" side is debatable (he is the antagonist after all), but a lot of his perversion is played for laughs.
- Obviously Evil: Meiko, Miku and Rin all see something wrong with him (Miku is even afraid that he's going to rape her). Kiyoteru can't be bothered to notice at first.
- Politically Incorrect Villain: Shows a fair bit of misogyny, including needlessly sexualizing Miku and Meiko and mockingly calling his female assistant "a housewife in training".
- Psychopathic Manchild: His sense of humor is ridiculously immature.
- Sinister Shades: Introduced with them and is clearly the story's villain.
- Slimeball: A pretty one, but a slimeball nonetheless.
Yuki Kaai
Voiced by: Space Cat, RawrKittyPanda (as a teen)
A close friend of Kaito's when he was a kid who showed skill with building robots of her own.- Ambiguously Evil: She's fairly reluctant to go through with Toshiro's plans, objecting that it's "stealing". However, she also openly mocks Miku when Toshiro holds her captive.
- Childhood Friends: With Kaito. He died when he was visiting her.
- Child Prodigy: Was able to build a fully functioning robot as a little kid.
- Deadpan Snarker: Especially toward Toshiro.
- The Dragon: Is working as an intern at Toshiro's company and appears to be personally helping him with his plan. She doesn't seem to like it though.
- Face–Heel Turn: She's now working for Toshiro.
- Girlish Pigtails: As a kid. Upgraded to a ponytail as a teen.
- Nice Girl: Even post-timeskip, where she seems to be working as Toshiro's dragon she's fairly nice.
- Punch-Clock Villain: She really doesn't like working for Toshiro. Then again, who would?
- Sailor Fuku: Wears one post-timeskip.
- Walking Spoiler: What she gets up to after Kaito's death makes her this.
