After losing his job at a high-tech corporation, Kiyoteru Hiyama suffers several further losses — his son, Kaito, dies in a car accident and his wife, Nanami, leaves him afterward. Kiyoteru tries to get by on a schoolteacher job, only to find that several of the robots he designed are being sent back to him, including a fembot named Meiko, a male robot named Shion... and a disc containing his son's brainwaves.
Kiyo quickly realizes that he has a chance to bring his son back, which he achieves by uploading the disc into Shion — now renamed "Kaito Shion", and soon ends up realizing that he also has a chance to get a stable job back. Unfortunately, his previous employers once again rejects him. But he is then approached by a man named Toshiro, who is willing to pay him for more robot designs.
From there, things get... complicated, especially since Toshiro has plans that may go against Kiyo's best interests...
Sadly, real life issues forced the series to a close before its time, but the creator left her viewership with one last video before pulling the plug — Season 2's intended opening theme
SHION provides examples of:
- Back from the Dead: Kaito, via Kiyo uploading his brainwaves into the Shion robot.
- Bare Your Midriff: Rin and Meiko.
- Big Bad: Toshiro is shaping up to be this.
- Bratty Half-Pint: Rin Kagamine.
- Childhood Friends: As a kid, Kaito was close friends with Yuki, though their parents didn't like each other. Yuki, unfortunately, saw Kaito die, and is working with Toshiro in the timeskip.
- Child Prodigy: Yuki was able to build a fully functioning robot when she was a little kid. Post timeskip, she's upgraded to a Teen Genius.
- Downer Beginning: Let's see, Kiyo is publicly mocked by his employer before getting fired, his son dies (after arguing with him) and his wife leaves him. Not exactly an optimistic opening.
- The Dragon: Yuki may be this to Toshiro, though how antagonistic she is is difficult to figure out.
- Does This Remind You of Anything?: The ways that Toshiro corrupts Kaito and Miku are uncomfortably (but fittingly) similar to a situation with a child molester and rapist respectively:
- With Kaito, he invites him over, talks to him like a friendly guy and asks him to trust him before telling him to let him touch a part of his body (his back, which is where his Personality Chip goes, not anything more...personal). He then orders both Kaito and Meiko to not tell anyone about it.
- With Miku, she's kidnapped off the streets and wakes up tied to a chair. With this one, the resemblance is lampshaded when Miku screams at Toshiro to "not take her flower", to which Toshiro is actually quite offended.
- Dumb Blonde: Len is implied to be this.
- Early-Bird Cameo: Haku Yowane, Gakupo Camui, Teto Kasane, Uta Utatane, Momo Momone, Ritsu Namine and Neru Akita all make an appearance in the season 2 ending song. Haku and Gakupo are apparently going to join Kiyo's True Companions while the rest are siding with Toshiro.
- Everyone Has Standards: Yuki's dad may have openly stated that he never liked Kaito and saw him as a bad influence, but he was clearly horrified at seeing him get hit by a car.
- Face Palm: Kiyo is guilty of doing this many times throughout the show.
- Happily Married: Played with—Kiyo and Nanami loved each other, but the situation they were in made things...tense. When they split up, it's primarily because both of them are emotionally vulnerable over Kaito's death and the constant issues with Kiyo's inability to maintain a steady job. Nanami even says that they're not getting a divorce, they just need some time apart.
- FaceHeel Turn: Yuki appears to have done this during the years between Kaito's death and revival.
- Girlish Pigtails:
- Miku has them, since Toshiro repeatedly demanded that Kiyoteru make a robot with pigtails. Rin uses them to insult her.
- Yuki has them when she's a child. They're upgraded into a ponytail when she grows up.
- Idol Singer: Miku, of course!
- Leaning on the Fourth Wall: In episode 4, Kiyoteru offers to show Toshiro Miku's singing prowess, and an initially reluctant Toshiro eventually agrees to listen. Cue the theme opening sequence, which is set to an English version of "World Is Mine" sung by Miku's voice actress. When it returns to the episode, Toshiro comments that Miku has a nice voice.
- Machine Monotone: Meiko starts out talking this way until she suffers a serious injury and has to get an upgrade—at which point she gains more of an actual personality.
- Manchild: Kaito, due to having the brain of an eight-year-old.
- MikuMikuDance: How the series is animated.
- Ms. Fanservice: Len comments that Meiko is "too pretty to be a mom".
- Naked on Arrival: Shion, due to being unfinished. Curiously, when Kaito is uploaded into him, he's less concerned with being naked and more concerned with being really tall.
- Red Eyes, Take Warning: Kaito and Miku when they're corrupted.
- Sex Bot: What Kiyo's potential boss initially thinks Meiko is. Kiyo's not pleased.
- Split Personality: Toshiro appears to have uploaded a short-tempered, murderous one into Kaito.
- Team Dad: Kiyo to the Vocaloids.
- Team Mom: Meiko, when she gets an upgrade.
- Time Skip: In the pilot episode, "Return to Gray", there's a five year gap between Kaito's death and his return as a robot.
- Tiny Tyrannical Girl: Rin towards pretty much everyone.
- Trademark Favorite Food:
- Kaito loves ice cream.
- Miku eats a leek once and immediately starts craving more. She even calls them "a true nectar of the gods".
- Len already states a love of bananas upon first activating.
- Rin states her liking of oranges.
- The Tease: Meiko playfully teases Kiyo about calling him Master.
- True Companions: Kiyo and his robots.
- Wham Line:
- From episode 1, when Kiyoteru tries to upload Kaito's brainwaves into the Shion robot...Shion: OW! Dad, that hurt!
- From episode 5, when Kaito and Kiyoteru are arguing:Kaito: Aren't I your son!?
Kiyoteru: [furious] NO YOU'RE NOT! YOU'RE JUST A MACHI— [realizes what he just said] crap.
- And shortly following that one, as Kaito storms off...Kaito: I'm going for a walk, dad. I mean... [venomously] master.
- When Kiyoteru and Miku are checking out a house for the family to move into, we get this:
- When Toshiro bids goodbye to his dragon, he addresses her thusly:Toshiro: I'm leaving. Take care of the house, Yuki.
- From episode 1, when Kiyoteru tries to upload Kaito's brainwaves into the Shion robot...
- You Gotta Have Blue Hair: Kaito Shion and Miku's hair is blue and green respectively. It's claimed that Kaito wanted to dye his hair blue when he was alive but Kiyo didn't let him.