It opens with a UFO appearing over the city (presumably Tokyo), panicking the air defense corps. One other effect is it identifies loners, recluses and pariahs, and "merges" them with housepets and other small fauna, creating nekomimi people. Mikami Inaba grew up in a broken home under a neglectful mother, becoming a street thug. She gets merged with Haru's pet rabbit Mimika, transforming into a bunny-girl. Nekoi Koshka was taunted as the daughter of a murderer, and came home one day to find her mother had hanged herself. Orphan Koshka gets merged with a black kitten she'd found.
A mysterious government agency learns about these "merged beings," and decides to quietly round them up for "experiments." When they discover that merged beings can exert low-level telepathy, it's decided that merged beings must be eradicated. Inaba-Mimika is targeted by government thugs, but her martial arts skills defeat them. In particular, a dog-man hybrid named Benten Chou sniffs her out, and an "admonisher" named Dekao becomes her personal nemesis.
There is a climactic showdown in a shopping mall, in which Inaba-Mimika rescues Haru and Miku. This heroic act succeeds in unmerging Inaba Mikami from Usagi Mimika. Haru regains his rabbit Mimika, and Inaba is finally welcome somewhere.
This anime provides examples of:
- Age-Inappropriate Dress: The girls' uniforms at Haru's high school have tops cropped just below the breasts, and extremely short skirts.
- Angry Cheek Puff: Miku twice develops bloated cheeks in frustration. The first occurs in class, as two of her classmates observe the bubbly, bouncy (and breasty) Mimika cuddling the serious and studious Haru. One girl wonders if this will trigger jealousy in Miku, and when the two girls look, Miku is seething: her hands are balled into fists, her cheeks are puffed out to the maximum, and a cow's mooing is heard. Yeah, she's jealous, for sure. The second instance occurs on the school's rooftop, where Haru keeps a rabbit hutch. Miku tries to get Haru to take her to a new burger shop in town, but Mimika appears and says that she and Haru can go home and eat the goodies they'd bought the day before. When Mimika looks at Miku, she wonders if Miku has gained weight, since her cheeks are once again puffed out in frustration.
- Bittersweet Ending: Inaba learns to value friendship and loses her distrustful, asocial demeanor. She gets welcomed back into the company of Haru and Miku. Benten Chou and Nekoi Koshka, however, must live as fugitives, having no friends or allies to help them.
- Black Site: The Public Welfare Board has been quietly rounding up merged beings, and using them for hideous, Nazi-like experiments. One poor squirrel-girl is seen being stripped of clothing, then shocked repeatedly with a cattle prod. Once the Director learns that merged beings can influence people with telepathy, he orders the merged beings to be wiped out completely. The Director even delivers his most feared "admonisher" by helicopter to slay the last ones: Koshka and Mimika. Very likely, poor Benten Chou would've been next.
- Buxom Beauty Standard: Of all the girls in Haru's class, Miku has the second-most developed breasts, a fact she knows well. Then Mimika joins Haru at school, pressing her G-cup boobs into Haru at every opportunity.
- Cat Folk: Nekoi Koshka is introduced at the end of chapter one. She's a Cat Girl with feline ears, swishy tail, sharp claws and vertical pupils amid golden irises. Koshka tends to refer to herself as a cat, although she's a "merged being," that is, a fusion of an orphan girl with a black kitten. Her fighting style is also catlike, with slashing claws and pouncing.
- Clingy Jealous Girl: Mimika can't get enough of Haru, and whenever Haru inquires about Inaba or Miku, Mimika tears up and flees.
- Clingy Sleepers: After Haru has taken the bunny-girl Mimika into his home, she insists upon sleeping in Haru's bed with him. This is normal for rabbits, who sleep huddled in a group to conserve warmth and to alert everyone to danger. As Mimika cuddles Haru, she reverts form to Inaba Mikami, an asocial Action Girl with a troubled past. It's out of character for Inaba to cuddle anyone; that she continues to cuddle next to Haru reveals that, despite her "shinigami" reputation, she secretly longs to belong with someone. Haru can only stroke her hair as she switches between Mimika and Inaba forms.
- Crash in Through the Ceiling: The Public Welfare Board uses a helicopter to drop a huge crate through the skylight of a shopping mall. Inside is Dekao, rebuilt yet again into a Giant Mecha on tank treads. This is his fourth try to eradicate Inaba Mikami and his first at slaying Nekoi Koshka.
- Ecchi: Four female bodies get exposed in detail. Breasts are bared, Jiggle Physics is demonstrated and nipples get seen, though labes are only suggested via a Panty Shot.
- Elite Mooks: Dekao is an "admonisher" (assassin) brought in when regular mooks don't get the job done.
- Electronic Eye: When Dekao is first seen, he has two normal eyes. After his fight against Inaba, he plummets off the school's rooftop. He reappears on the public beach rebuilt with a camera-like right eye, plus rocket fists and shoulder-mounted missiles. During his last appearance, the audience is shown a view through this eye as it targets Inaba and Koshka.
- Expressive Accessory: Benten Chou has a hachimaki (headband) that displays different phrases, depending on Chou's circumstances. These messages range from "one fixed pattern" to "it's a good time to leave." There are 29 such messages in total.
- Feeling Your Heartbeat: After Inaba has defeated Dekao on the public beach, she switches to her Mimika form. As Haru tries to sit up after being beaten down by the Muscle Beach Bums, Mimika burbles that she'd been so scared that her heart is racing. She puts Haru's left hand on her sternum, urging him to feel her heartbeat. Miku protests that Haru is getting to feel Mimika's huge boobs.
- Fireball Eyeballs: Miku's irises burst into flames at the sight of humanoid Mimika wriggling and snuggling Haru on his bed.
- Full-Conversion Cyborg: The end result of Dekao's Serial Prostheses. In his first fight, he's 100% human. His rematch happens on a public beach, after Dekao has had an Electronic Eye, rocket fists and shoulder-mounted missiles installed. His third attempt to slay Inaba has Dekao reduced to a head and torso attached to a mechanical horse's body, looking like an armored centaur. His final match at the shopping mall has Dekao reduced to just his head directing a huge war machine on tank treads. He still loses, going 0 for 4.
- Full Moon Silhouette: At the start of chapter 3, Mikami Inaba concludes her soul searching, and leaves the sixth floor apartment via the terrace. She leaps into the night sky in front of an oversize moon that frames her completely. This moment freezes as a cut point to another scene, that of Haru and Chou conversing in a by-street.
- Funny Animal: Benten Chou is an irritable little runt who was merged with a dog. Unlike the nekomimi, his animal form has face fur, an elongated snout, and a dog's nose in addition to canine ears and tail.
- Giant Medical Syringe: Mika Mizumi has volunteered to perform cosplay at a school fundraiser, choosing to wear a Naughty Nurse Outfit, complete with a giant syringe as a prop. The mostly male crowd reacts strongly when Miku straddles the thing coquettishly.
- Head-Turning Beauty: New student Nekoi Koshka comes to visit Mimika in her homeroom. She's brought a corps of drooling boys with her, and shuts the door in front of them. The boys continue to drool at Koshka through the window. During the Cultural Festival's beauty pageant, Koshka garners the most spirited cheers and hoots as she slinks around on stage.
- Heel–Face Turn: Benten Chou is a merged being exploited by the Public Welfare Board to sniff out other merged beings. When Chou sees just how backstabbing and ruthless his bosses are, he decides to help Haru and Miku escape from the shopping mall.
- High-Speed Missile Dodge: Every time Dekao is rebuilt, he gets a new set of missiles, which he launches against Mimika. However, being a bunny-girl, Mimika is too fast and agile to be hit by any missile, so three times Dekao runs out of missiles without hurting Mimika.
- Imagine Spot: Miku imagines herself and Haru as naked newlyweds. Later, Miku learns that Mimika has "slept with" Haru (just sleeping, no hanky-panky) and imagines Mimika and Haru as a naked couple.
- Indirect Kiss: Haru allows Mimika to taste his cola, though she was unprepared for its fizziness, and starts coughing. As Haru takes her to a wash station, Miku sees Haru's unfinished cola, and ponders sipping it herself as an indirect kiss. Miku blushes and puts the cup down, ashamed that she almost used such a desperate tactic.
- Jedi Mind Trick: Merged being can emit low-level telepathy that makes their animal features seem commonplace. Mimika appears suddenly in Haru's household, but no one there thinks she's in any way out of place. Mimika explains to Haru that her bunny ears can project a "nothing weird here" telepathy that makes her an Unusually Uninteresting Sight.
- Male Gaze: While the characters are conversing and clothed, the POV is usually at eye level. When Mimika is getting snuggly with Haru, the POV is breast-level, and all other times, the POV is an upskirt view from about knee-level. Even Haru takes a moment to appreciate the feminine curves of Mimika and Miku in swimwear.
- Muscle Beach Bum: Three of them, with muscular frames, swim goggles, bathing caps and speedos, calling themselves the "Sailors of Sinbad." They get lewd with Miku, and make short work of Haru. This is a Batman Gambit by Benten Chou, because the antics of the "Sailors" trigger Mimika to transform into Inaba Mikami.
- Naughty Nurse Outfit: Miku dons one during a school fundraiser. She makes a suggestive pose with a giant syringe prop that elicits hoots and cheers from the mostly male audience.
- Nipple and Dimed: Not even slightly. There are four main female characters: Miku, Inaba, Mimika and Koshka, and all four bare their breasts at some point. For those taking inventory, all eight nipples are accountable.
- Panty Fighter: Almost every female character wears ultra-short skirts, and the combative Action Girls, namely Inaba and Koshka, routinely high-kick and gymnast flip. It'd be hard not to notice that Inaba's panties have a frilly pocket on the front, as it gets shown many times. Koshka's skirt has a slit up the back to accommodate her swishing tail, so her panties are always exposed from the rear, and yield a complete view while Inaba has her in a wrestling clinch.
- Pocket Rocket Launcher: When Dekao faces Inaba on a public beach, he manages to punch her in the midsection with a rocket fist. This blow knocks her into the sea. There, she commandeers a jet-ski, and attempts to ram Dekao with it. To Inaba's surprise, Dekao deploys launch tubes from his shoulders, loosing six missiles in total at her. Inaba jumps clear just before the missiles destroy the jet-ski.
- Power Dyes Your Hair: As Mimika, she's a fragile blonde with the mind of a rabbit, prone to fleeing when confronted. As Inaba, she's an ass-kicking raven-haired Action Girl that makes lesser mooks flee from her.
- Removed from the Picture: At the start of chapter 3, Miku is wearing a bath towel, and admiring a framed photo of herself next to Haru, who's being hugged by Mimika. Miku positions a beverage glass in front of the photo, obscuring most of Mimika, which is a Downplayed Trope. With only the faces of Miku and Haru visible, Miku begins trying out various come-on lines to get Haru to ask her out.
- Rivals Team Up: Inaba Mikami and Nekoi Koshka continue their duel in the Ayakagi Mall, until a new combatant enters the fray. It's Dekao the Admonisher, rebuilt yet again into a war machine on tank treads, and he's there to slay both of them. The first weapon Dekao deploys is his whirling tentacles, which Inaba easily dodges. Koshka, however, was caught by surprise, and suffers Clothing Damage. When Dekao retracts his tentacles and deploys a missile launcher, Inaba carries the fallen Koshka to safety behind some debris. Once Dekao is out of missiles, Inaba invites Koshka to engage him in combat, using the term "partner." Koshka is flummoxed by this, but follows Inaba's lead nonetheless. Together the two girls defeat Dekao with Teeth-Clenched Teamwork.
- Serial Prostheses: The "admonisher" Dekao squares off against Inaba Mikami four times in total. After each defeat, he gets cybernetic upgrades.
- Starts out with no cybernetic parts. Falls off the school's rooftop.
- On the public beach, Dekao has an Electronic Eye (right) installed, plus rocket-propelled fists and six shoulder-mounted missiles. Gets splashed with seawater, shorts out, explodes.
- At the school fundraiser, Dekao has missile launchers in each forearm, and from the waist down, he's a mechanical horse: a cybernetic centaur. One good kick to the head by Inaba makes him short out and explode.
- In the shopping mall, Dekao is just a head directing a war machine on tank treads. He gets a power cable stuffed into an access panel, which electrocutes him and makes him explode.
- Shock Stick: The ruthless director of a Black Site has ordered his minions to round up all the merged beings in Tokyo, and use them for hideous, Nazi-like experiments. One poor squirrel-girl has her clothes ripped off, then receive a merciless shocking from a faceless mook that's using an electrified baton. The Director makes no secret that he harbors a fierce animosity for any merged being, and aims to expunge them from Tokyo entirely.
- Smoke Shield: When Dekao confronts Inaba on the beach, she tries to attack him with a Jet-Ski. Dekao suddenly deploys launch tubes from his shoulders, loosing six missiles at Inaba. Her Jet-Ski gets blown to smithereens, producing a large blast flash and billowing smoke cloud. However, Inaba saw the missiles coming and bailed from the craft before it was destroyed, landing a short distance in front of Dekao, showing no sign of damage.
- Surrounded by Idiots: Benten Chou has brought a corps of mooks to apprehend the bunny-girl Mimika. As she exits Haru's tent, she sees them, and promptly leaps over their heads. The mooks are so awestruck that none think to pursue her. Chou has to roar "Idiots! After her!"
- Three-Point Landing: Inaba leaps high into the air to attack Dekao, who has been rebuilt into a cybernetic centaur. He's out of missiles, so he can only watch as Inaba gains enough momentum from gravity to deliver a devastating kick to his head. She lands behind him in a three-point stance: right foot, left knee, left hand, with her right hand pulled away and behind. Dekao then shorts out and explodes, while Inaba, still in that stance, snarks that Dekao will need his brain repaired.
- Unusually Uninteresting Sight: Enforced by telepathy from merged beings. Mimika's bunny ears and fluffy tail pass for normal, as does Koshka's cat ears and swishing tail. In fact, their classmates and many mooks tend to start Eating the Eye Candy rather than decrying the nekomimi.
- Wacky Homeroom: Students in Haru's classroom seem to have the run of the place, as the teacher is only seen once, escorting Koshka from the headmaster's office. Haru studies his animal care books and keeps a rabbit hutch on the school's roof. Miku tries to get the oblivious Haru to take her out, and orbits his desk. Humanoid Mimika straight up spends the school day hugging Haru, using her low-level telepathy to convince everyone else there's nothing weird about that. The girls in the classroom even conduct a fundraiser by strapping Miku and Mimika to plasterboard, and have boys pay to be a firing squad using paper blowgun darts.
- We Can Rebuild Him: Admonisher Dekao squares off against Inaba Mikami four times, losing each time. After each defeat, Dekao returns rebuilt with cybernetic parts. In his last battle, Dekao is just a head directing a Giant Mecha on caterpillar treads. He still loses.
- You Have Outlived Your Usefulness: The regular mooks realize that their bosses are perfectly willing to expend them in order to eradicate merged beings, and leave no loose ends to the genocide.
