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Literature / My Vampire Older Sister and Zombie Little Sister

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"If a zombie and a vampire went all out, which one would win?"

For most people, this would just be an idle thought that leads nowhere. But unfortunately for Satori Amatsu, an Ordinary Japanese high school student, he says it out loud. And as it happens, he's overheard by his vampire older sister Erika and zombie little sister Ayumi. It starts an argument, which eventually leads to the two deciding to prove which one is stronger. They then use their powers to start two warring pandemics, aiming to crush the other...


But only in virtual reality. Prior to this, Satori had constructed a miniature supercomputer, nicknamed "Maxwell", for the purpose of simulating natural disasters. However, he'd ended up using it for less noble purposes, and his sisters blackmail him into using it to simulate their battle. But it doesn't end there. It turns out that if his childhood friend and neighbour "dies" in the simulation, the data will be sent to others, including evidence of the less noble use of the simulator. As a result, Satori has to enter the simulation himself and go to any lengths to keep her virtual self alive. Inside, he discovers that there's far more to the world than he first thought...

My Vampire Older Sister and Zombie Little Sister is a web novel series by Kazuma Kamachi released on his official website.


This series provides examples of:

  • Aerith and Bob: There are two siblings whose first names are Helen and Tamago. The former is mentioned to be half-Japanese, so it's possible that they're half-siblings.
  • A.I. Is a Crapshoot: Subverted. While Laplace, the supercomputer owned by the Bright Cross, is used for evil, it doesn't do anything of its own accord. Not only that, but it switches sides to Satori at the end..
  • All Myths Are True: Monsters and creatures from myths and folklore all across the world appear to be real species, not to mention the fact that both Valkyries and demons like Lilith exist.
  • Apathetic Citizens: The inhabitants of Kukyou City, by and large, don't see anything wrong with the Colosseum. On the contrary, many of them are even excited, as if it were a normal sporting event.
  • Apocalypse How:
    • The virtual Kukyou City undergoes a City variant, with every human being killed, or turned into a zombie or vampire.
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    • The Calamity is a potential Planetary example - Lilith claims that humanity would become extinct if no countermeasures were taken. The very end of Volume 3 suggests that it's the gradual breakdown of people's empathy for one another, which would eventually lead to the collapse of society.
  • Arbitrary Skepticism: Satori initially expresses some doubt that dark elves actually exist beyond RPGs and fantasy light novels, viewing the concept of a dark elf as more fantastical and otherworldly than a vampire or a zombie. Apparently, he's not a fan of Norse Mythology.
  • The Ark: According to Lilith, the world will soon come to an end, so her group is preparing one of these to preserve as much as possible. It's called Absolute Noah, though it's not clear whether it's a literal ship, an underground shelter, or something else. Due to space limitations, it will only be able to hold a few thousand humans, plus genetic samples from the remaining human population and about 36% of the world's organisms. Volume 4 reveals that only the most moral subset of society will be allowed on to the real Absolute Noah (numbered 00). Fourteen other "arks" have been created as traps for those people who are willing to throw aside others to secure their own safety - these arks appear sturdy on the surface, but don't actually protect their inhabitants at all.
  • Armor-Piercing Attack: Tamago Itou uses a sniper rifle with special ammunition made from a metal denser than lead, capable of piercing bulletproof glass.
  • Authority Equals Asskicking: The Bright Cross Foundation turns out to actually be led by powerful Archenemies such as Valkyries.
  • Awesomeness by Analysis: Maxwell, as an environment simulator, can take in data from practically any situation and come up with solutions. Laplace, having more processing power, is even better at this.
  • Badass Family: The Amatsu family. Satori managed to build a supercomputer out of video game consoles, while Erika and Ayumi could easily cause the destruction of a city. Taizou, Satori's father, turns out to be a former member of the Bright Cross's moderate faction. Yurina, Taizou's second wife and the siblings' stepmother, is none other than the Lilith of legend, an Archenemy capable of easily defeating both Erika and Ayumi in a fight. Last of all, Taori (Taizou's first wife and Satori's mother) has apparently been enhanced to the point that she can fight equally against Yurina.
  • Badass Normal:
    • Satori, using his knowledge of the supernatural and with help from Maxwell, manages to put up a good fight against the superhuman Archenemies.
    • An even bigger example is Tamago Itou. A skilled sniper who works for the Bright Cross, he manages to be a serious threat against three opponents, two of which are Archenemies, and while unsure of himself!
    • The US soldiers in Volume 4 are a small army of these. They're capable of surviving in a city filled with hostile and seemingly invincible gels and where half of the population are Archenemies. One of them manages to get the upper hand against Ayumi in a close-quarters fight.
  • Baleful Polymorph:
    • A Circe witch can brew potions to transform others into any kind of living thing. Though the examples featured in Volume 2 actually benefit the victims: Helen transforms her opponents into enormous monsters, ensuring that they can survive the execution method used on them.
    • At the beginning of Volume 3, Satori finds himself in the form of a giant garlic. Somehow, he's able to move, talk and sense his environment.
  • Beauty Is Never Tarnished: Averted. Many of the female characters suffer horrific injuries, including broken bones, having their head destroyed, being gradually eaten alive by zombies...
  • Benevolent A.I.: Maxwell, the AI created by Satori is an incredibly helpful sidekick. At most, it will snark at Satori's dumber moments. It even comforts him after he causes the fall of the Bright Cross Foundation, which ends up causing significant international chaos due to the organization's humanitarian campaigns suddenly stopping. Laplace, the supercomputer owned by the Bright Cross that is used against Satori and Helen Itou in the second volume, turns out to be similarly benevolent, helping Satori and the others as much as it can from its position as an enemy tool.
  • Bling-Bling-BANG!: Karen fights using a spear and shield made from solid gold.
  • Bloody Hilarious: Erika finds herself unable to create vampires quickly, as she has to suck a lethal amount of blood to turn them, so just one person fills her up. Her solution? Vomit it all out.
  • Brick Joke: In the middle of the first volume, Erika (as part of a ploy to get an invitation) promises to tell Satori where she starts washing during a bath. At the end, she actually goes through with it.
  • Broke Your Arm Punching Out Cthulhu: Satori eventually stops Erika's and Ayumi's fight by running between them, getting bitten by both simultaneously. It does stop them fighting, though he 'dies' in the simulation as a result.
  • Caught with Your Pants Down: Played for Laughs in the first chapter of Volume 2. Erika and Ayumi are angry at Satori for accidentally stealing a rare brand of bread from them, so he gives Maxwell free rein in distracting them. Maxwell accomplishes this by imitating Satori's voice and loudly yelling out that they interrupted "him" in the manner of this trope. It actually works, in that it leaves the sisters too stunned to respond... but the entire neighborhood hears it as well.
  • Cerebus Syndrome: Shifts from lighthearted Black Comedy to fighting against the Bright Cross at the end of Volume 1.
  • Chainsaw Good: The weapon used by the final enemy in Volume 3 looks like an oversized chainsaw with three alternating blades, with an additional crossbow attached to the top.
  • Chekhov's Gunman: The list of simulated victims at the end of Volume 1 includes the siblings Helen and Tamago, both of whom are important in the next volume.
  • City of Adventure: Kukyou City, which is often subject to natural disasters and has a high population of Archenemies.
  • Clueless Chick Magnet: Satori is completely unaware about the feelings of Erika, Ayumi and the Class Rep towards him. While the last of these at least tries to be discreet, the first two are extremely open about it. For just one example - in Volume 3, Satori recalls Erika telling him the story of the Polish Vampire Princess. He remembers that it ended with a knight turning the princess into a human and marrying her, which Erika became excited at. He then wonders why she told him that story.
  • Cold Iron: Iron is mentioned to ward off evil, particularly being useful as a passive talisman against things like fairies, for example, by hanging a horseshoe in the front door.
  • Cold Sniper: Tamago Itou in Volume 2. Also subverted, as he's constantly doubting himself after being ordered to kill his younger sister, and eventually pulls a Heel–Face Turn.
  • Colony Drop: Moon Mortality, a terrifyingly powerful attack in which many vampire minions transform into bats and fly up to the stratosphere. They collectively form a mass weighing hundreds of tons, which then falls to the ground at terminal velocity. A single use can reduce an entire central business district to a crater.
  • Cool Big Sis: Invoked by Erika.
  • Cool Versus Awesome: The very first volume revolves around a (virtual) battle between a vampire and a zombie, using everything at their disposal.
  • Creature Hunter Organisation: The Bright Cross Disaster Prevention Foundation has the purpose of fighting all disasters, and sees the Archenemies as part of this.
  • Cyberspace:
    • Maxwell can create one of these, designed to simulate Kukyou City undergoing various natural disasters.
    • The Ghost in Volume 3 can also do this, trapping Satori in a simulation as part of its plan.
  • Dating Catwoman: Satori's father, a Bright Cross member, is married to the Archenemy Lilith.
  • Demon Lords and Archdevils: Lilith, the mother of succubi, is described as a demon lord. She is incredibly strong, capable of overpowering a vampire and a zombie simultaneously.
  • Devil in Disguise: Yurina, the siblings' stepmother, is a literal example, being the Archenemy Lilith.
  • Did You Just Punch Out Cthulhu?:
    • Satori manages to defeat Karen with a completely ordinary pen, albeit only with Laplace's help.
    • He later manages to incapacitate Lilith using electric shock, after first tricking her into thinking he'd trapped her in a simulation.
  • Distracted by the Sexy: Erika exploits this to trick Satori into inviting her into a building. Specifically, she calls his smartphone and claims that she'll put on a strip show for him. Satori, thinking that she means to do it over said phone, agrees.
  • The Dreaded:
    • After the simulation is complete, Ayumi and Erika become this to the Bright Cross, which had simulated the same scenario using their own supercomputer. The Bright Cross is then unwilling to try to harm Satori, for fear of provoking the sisters' wrath.
    • At the end of Volume 2, Satori becomes this to the mysterious organisation behind the Bright Cross. With a veritable army of Archenemies on his side (potentially including a powerful Valkyrie) and both Maxwell and Laplace (albeit with the latter weakened), he's now seen as a serious threat that has to be dealt with as soon as possible.
  • Dude, She's Like, in a Coma!: A kind-of-consensual example. When she's about to enter the simulation, Erika tells Satori that he can do whatever he wants to her unconscious body, as long as he doesn't dirty her hair or clothes. He doesn't do anything.
  • Duel to the Death:
    • Erika's and Ayumi's fight in Volume 1 ultimately devolves into this. Satori stops it before either of them gets the upper hand, 'dying' himself.
    • This method is also used by the Bright Cross to execute particularly tough Archenemies. It becomes the standard format of the Colosseum in Volume 2.
  • Eldritch Abomination: A Shoggoth is mentioned in the Bright Cross' files on dead Archenemies. Unlike other Archenemies, it's unclear what its former identity was... if it was ever human at all.
  • Evil Counterpart: Laplace is this to Maxwell, a vastly more powerful supercomputer that is used by the Bright Cross. Subverted, in that it isn't evil itself.
  • Extranormal Prison: The Bright Cross' underground facility was used to contain Archenemies, prior to their execution.
  • Fantastic Racism: The Bright Cross aims to exterminate Archenemies because of this. Actually subverted, because they're secretly led by Archenemies. They experienced prejudice from humans, so created the organisation as a means of directing and controlling this hatred.
  • Fighter, Mage, Thief: The three Amatsu siblings could be seen as this:
    • Ayumi is the fighter, preferring brute force and creating a large number of zombies to swamp the enemy with numbers. If human zombies prove too weak, her solution is to use stronger and faster animal zombies.
    • Erika is the mage. She prefers to work from behind the scenes, using her various vampiric abilities, which are more overtly-supernatural than a zombie's.
    • Satori is the thief. As a normal human, he can't fight Archenemies or combat-trained humans head-on. Instead, he makes use of Maxwell to provide intel, hack electronics, and plan tactics and strategies.
  • Foreshadowing: Throughout Volume 1, there are hints of something going on: an advanced drone observing the outbreak at the school, a tour bus containing The Men in Black. These are all related to the Bright Cross.
  • Friendly Enemy: Erika and Ayumi are this in Volume 1 and at the end of Volume 2.
  • Full-Name Basis: Satori addresses everyone except Erika, Ayumi and the Class Rep with their full names.
  • Half-Human Hybrid:
    • Elves can have part-elven offspring with humans. This is why they're considered an Archenemy, as it allows them to "infect" the human population.
    • Half-Valkyries, children of Valkyries and human men, are also mentioned to exist and have excellent potential as warriors.
    • Vampires can also do this, producing dhampirs. Dhampirs have yet to make an appearance, but according to Erika, they have both a human side and a vampire side. They can tap into their vampiric powers to protect humans (by hunting vampires), but if they are consumed by their power, they will become vampires themselves.
  • Healing Factor:
    • Vampires can rapidly regenerate from any injury not caused by one of their weaknesses.
    • Helen can make potions that accelerate healing.
  • Heart Is an Awesome Power:
    • Helen's ability to make potions that transform people might seem weak at first, especially since she herself is otherwise human. But said potions make her possibly the most versatile Archenemy in the series: she can heal, strengthen herself, instantly defeat enemies by transforming them into something helpless, and create minions with much more control than a vampire or a zombie. With Satori's help, she manages to defeat both Erika and Ayumi simultaneously!
    • In this setting, dark elves only have two minor supernatural powers (besides a long lifespan): elflock and elfshot. The former allows them to tangle up elongated objects like shoelaces, the latter is an invisible arrow (actually iron powder carrying an electric charge). However, it turns out that being able to trip up your opponent from a distance, with no apparent countermeasure, is extremely useful in a fight. And the invisible arrow can't be handled using the same means as a normal projectile, since it isn't a normal projectile.
  • Heel–Face Turn: Towards the end of the second volume, both Tamago and Laplace do this.
  • Hemo Erotic: Erika expresses a desire to suck Satori's blood that sounds a lot like... something else. Since this is happening in the simulation, she nearly ends up going through with it.
  • Hollywood Hacking: Maxwell is a frequent offender.
  • Humans Are the Real Monsters:
    • One of the themes of the series is that humans can be just as evil as any supernatural monster. It's especially pronounced in the second volume.
    • Parodied in a brief instance, when Ayumi says that if the Class Rep ever found out about the Sexy Class Rep Dance File Folder, she'd demonstrate this trope.
  • Hypocritical Humor: Satori tries to chastise his sisters for wanting to use Maxwell, his disaster environment simulator, to settle whether vampires or zombies would win in a fight by claiming it's only meant to be used to simulate serious scenarios. The two immediately reveal they know he himself has used it to simulate alien invasions and wars between giant robots, not to mention making a model of the Class Rep dance in a bikini for him.
  • Improbably Female Cast: So far, all of the major Archenemy characters are female. The only males seen so far are the vampire and zombie minions in Volume 1, and someone referred to as "Berserk" who dies offscreen.
  • Kill It with Fire:
    • One way to kill vampires.
    • The gels in Volume 4 can be repelled by fire (and intense heat in general), but it doesn't seem to seriously harm them.
  • Little Sister Heroine: Invoked by Ayumi.
  • Laser-Guided Amnesia: Whenever Satori sees the final monster in Volume 3, he temporarily loses his memory of it. He notes that this makes it difficult to deal with, comparing it to Medusa from Greek mythology. This isn't supernatural at all - it's because said "monster" is in fact his biological mother, and his mind refuses to accept it.
  • Loads and Loads of Characters: The end of Volume 1 contains a list of 65 characters who died in the simulation, with their names, backgrounds, and causes of death.
  • Long Title: And it's not just the series' title. The title for every single volume starts with these words, followed by more text that describes that particular volume.
  • The Man Behind the Man: The Bright Cross turns out to be no more than a cover for another mysterious organisation.
  • Man of Kryptonite: Satori has the form of a giant, mobile garlic at the start of Volume 3, making him this to vampires. Conveniently enough, the first villain is a vampire.
  • Men Are the Expendable Gender: Averted. Men and women alike die in droves in the simulation in Volume 1.
  • The Men in Black: The agents of the Bright Cross.
  • Monster Town: Half of the population of Las Vegas are Archenemies, making it the largest single concentration of Archenemies in the world.
  • Morton's Fork: Volume 2 has two examples. Satori can let Ayumi and Erika fight, which would lead to one dying, or he can try to have Helen intervene, which would probably lead to her dying. After that's resolved, he's faced with another dilemma: either withholding his information on the Bright Cross, allowing them to continue persecuting Archenemies; or releasing the information, which would destroy the Bright Cross, but also stop all of their charitable works and cause great societal upheaval. In both cases, he chooses the second option.
  • My God, What Have I Done?: Satori has this reaction after releasing information about the true nature of the Bright Cross. While it did stop their persecution of Archenemies, it also stopped their charitable work, incited riots, and boosted crime in several places.
  • N.G.O. Superpower: The Bright Cross Disaster Prevention Foundation.
  • Not Blood Siblings: Satori, Erika and Ayumi are stepsiblings. The latter two became part of the Amatsu family when Satori's father remarried.
  • One Curse Limit: It's impossible for a vampire to infect a zombie or a zombie to infect a vampire. When Satori is bitten simultaneously by Erika and Ayumi, he "dies" before either infection can take effect, so it's still up in the air which one would take priority. Averted by a Circe witch's potions, which can transform an Archenemy into another type of Archenemy (though they've yet to be used on a zombie or vampire).
  • Only Known by Their Nickname: Satori's childhood friend is only ever referred to as Class Rep, occasionally with "Forehead" and/or "Glasses" appended to the front.
  • Our Monsters Are Different: Known as "Archenemies" in-universe. They have several defining characteristics: surpassing conventional biology; a lifespan that is either infinite or immeasurably long; originating from or being created by a human; and being able to infect humans in some way.
    • All Trolls Are Different: A Troll is one of the Archenemies captured and frozen by the Bright Cross Foundation.
    • Blob Monster: The gels that serve as the major threat in Volume 4. They're red in color, consume any kind of organic matter, and sense their surroundings by tasting particles in the air. They were originally Shoggoths, a type of Archenemy found in Antarctica, which were modified in Area 51 to make them aggressive and animalistic.
    • Harping on About Harpies: A Harpy is one of the Archenemies captured and frozen by the Bright Cross Foundation.
    • Our Cryptids Are More Mysterious: An Aka Manto, a Japanese urban legend, is one of the Archenemies captured and frozen by the Bright Cross Foundation. One of the Archenemies commenting on the online video Yurina made of Satori saving the Class Rep and defending the fair treatment of Archenemies claims to be a Yeti that's keeping a low profile.
    • Our Elves Are Different: While only dark elves have appeared so far, they aren't that much more powerful than humans. Aside from being long-lived, they have some weak magical abilities.
    • Our Fairies Are Different: A Leanan Sidhe is one of the Archenemies captured and frozen by the Bright Cross Foundation and one appears in Volume 2 as one of the fighters in the Colosseum. She can grant people inspiration but drains their life force in return. Additionally, only people designated as her lover can see or touch her.
    • Our Mages Are Different: Some Archenemies, despite basically being just humans with magic powers, are considered Archenemies because they are born with their powers. Helen is a Circe witch, a variant that (like the mythological Circe) can make potions that turn people into animals or even Archenemies. However, normal humans that gain magic powers through study and learning (for example, the Voodoo bokor) are not classified as Archenemies.
    • Our Mermaids Are Different: Western and Eastern mermaids are mentioned to exist. Western mermaids are considered man-eating monsters that can control people with their voice, and also have power over rocks. The latter ability is because mermaids are considered to be the symbols of unexpected shipwrecks caused by reefs and rocks. The Western mermaid that appears in the story has the lower half of a human but can wrap her long hair around her legs to form a fish-like tail, drawing speculation that she might belong to a Selkie-like subspecies.
    • Our Vampires Are Different: They have most of the usual strengths (Super Strength and Super Speed, transforming into animals, regeneration from anything other than their weaknesses) and weaknesses (direct sunlight, running water, needing an invitation, no reflection, silver weapons, wooden stakes, garlic). What stands out are their need to suck a lethal amount of blood to turn a human into another vampire (roughly 1-2 liters) and that each vampire has a unique skill (comparable to genetic mutations). In-universe, the latter is used to explain the different variety of vampires in legends. Several subspecies of vampires are mentioned, like Upior, Kallikantzaros, Nelapsi and the Varcolaci.
    • Our Werewolves Are Different: They incorporate a broad interpretation of a wolf's abilities into a human body, so they have the usual traits of super strength, super speed, superhuman senses beyond those of even a normal wolf, regeneration and a weakness to silver. They are powerful enough that they get easily confused with vampires, another notable nocturnal Archenemy species, a confusion only furthered by how vampires share their weakness towards silver and many vampires can also transform into wolves. However, while they can shift into a wolf form and a human form, they stand out because that human form can be ''any'' human form, so can impersonate other people down to their clothing. Their 'true' human form has wolf ears, wolf tail and an upper body covered in thick, hard fur. It's also notable that while their weakness to silver is not necessarily lethal, they cannot physically damage silver, so even a mere silver-coated object can be a perfect shield. It is left unclear if humans can be turned into werewolves, while stories mention a human killed by a werewolf will become one there's no reports of them infecting the population like vampires or zombies do.
    • Our Zombies Are Different: They can be up to 10 times stronger than they were in life, but this depends on their state of decay. They can only be killed by destroying their brain, and any other injuries they have can be fixed by sewing themselves together. They don't heal normally, however, and they rot constantly unless treated with preservatives. Their bite turns others into zombies, and it isn't restricted to humans - it can infect other kinds of animals and even plants.
  • Person of Mass Destruction:
    • Any Archenemy has the potential to be this, thanks to their ability to influence humans. Mermaids can control entire crowds with their song. Witches can transform humans into other forms (including Archenemies) using potions. And as the simulation in the first volume shows, zombies and vampires can easily cause the destruction of an entire city, even one with anti-Archenemy measures.
    • The Upior, a vampire variant, stands out even among vampires. It has the ability to kill everyone of the same age as it by ringing a church bell. Not only that, but it can bite people discreetly using a tongue like a mosquito's proboscis, and everyone who is bitten and is killed by the bell will be transformed into a vampire.
  • Post-Modern Magik: There's a lot of instances of the supernatural being combined with technology. The premise of the very first volume is using a supercomputer to simulate a vampire and zombie's battle. In the second, Satori uses his supercomputer to assist the witch Helen in her use of potions. This involves things like looking up useful animals for her to transform into. And then there's the Valkyrie who uses her own, more powerful supercomputer, making her invincible in combat.
  • Power Perversion Potential: Maxwell is an incredibly powerful supercomputer, capable of realistically simulating an entire city experiencing a natural disaster. Satori uses it to simulate a model of the Class Rep in a bikini (the "Sexy Class Rep Dance File Folder"), complete with Jiggle Physics.
  • Redemption Demotion: Laplace loses much of its processing power when Satori retrieves it. This is because he couldn't possibly transport and store all of its original form (which took up a gymnasium-sized space), so he could only retrieve the component containing Laplace's personality. Though Satori accuses Maxwell of intentionally cutting Laplace's specs so that it's slightly inferior in order to keep Satori's interest from shifting towards the new AI.
  • Required Secondary Powers:
    • Helen's ability to brew potions comes with an instinctual understanding of chemicals and chemistry equipment.
    • A non-supernatural example can be seen in the requirements of a large supercomputer. Among other things, it needs a large amount of power, significant cooling capabilities, a stable environment, and protection from hazards such as dust and vibration. Satori uses these to deduce the location of Laplace in Volume 2.
  • Self-Duplication: Satori, as a giant garlic, is capable of this. By touching soil and water while exposed to sunlight, he can split himself into eight copies. Each copy is just as capable as the original, and can also duplicate themselves. However, making too many copies reduces his control over them, as his mind can't properly handle the burden of so many bodies.
  • Seven Deadly Sins: There are several theories for which Demon Lord represents which sin, so there's multiple Demon Lord candidates per sin, with some Demon Lords qualifying for more than one sin depending on the theory and alternate names making things even more confusing. For example, Belphegor, Lilith, Astaroth are considered to fall under Sloth, but Belphegor also fits under Lust.
  • Shapeshifter:
    • Vampires can transform into a variety of different animals. Bats are the most common, but moths and butterflies have also been used and wolves are mentioned to be another common transformation for vampires.
    • Circe witches, like Helen Itou, can brew potions that turn the drinker into an animal or Archenemy.
    • Werewolves can naturally transform between human and wolf forms. The human transformation doesn't necessarily need to be a transformation into 'their' human form, and they can impersonate other humanoids down to their clothing.
  • Silver Has Mystic Powers: Silver can ward off evil, so it's useful against certain Archenemy species like vampires or werewolves. Unlike iron, which has passive meaning and is used more for talismans, silver has an active meaning and is used more for offense with things like silver bullets.
  • Supernaturally Young Parent: The Amatsu siblings' stepmother Yurina could easily pass for a college student. Justified, as she's an immortal Archenemy.
  • Superpower Lottery: Archenemies vary greatly in power, from relatively weak (e.g. dark elves) to extremely strong (vampires, zombies. That's not getting to the likes of Valkyries, which can't even be killed permanently.
  • Take a Third Option: At the end of Volume 3, when Satori is faced with the option to help either his mother or his stepmother (currently fighting to the death), he jumps in between them. Both of them stop their attacks just in time, and his mother retreats.
  • Thou Shall Not Kill: Helen Itou will not kill anyone, even if they're trying to kill her.
  • Tournament Arc: Savagely deconstructed with the Colosseum in Volume 2. Every fight is meant to be to the death, as it's all intended as a means of executing Archenemies.
  • The Unmasqued World: Archenemies are publicly known, to the point that a tournament about them fighting is broadcast on international television.
  • Uninhibited Muscle Power: The source of a zombie's enhanced strength. However, due to their inability to heal and constant rotting, their strength will decrease over time until they are weaker than when they were alive.
  • Unusually Uninteresting Sight: Despite it being publicly known that Archenemies exist, no-one seems to pay much attention to Ayumi or Erika, despite the former having stitches all over her body and the latter never going out during the day. After the end of Volume 2, in which they fight on live television, it remains to be seen if this will change.
  • Valkyries: Karen turns out to be one. They're among the most powerful Archenemies in the series, strong enough to wield solid gold weapons with ease and fast enough to parry bullets.
  • The Virus: The zombie pathogen (officially known as "Acute Zombie Powder") and the vampire curse. Notably, while vampires are utterly under the control of their creator, zombies are not. Zombies will follow their instinctive hunger above all else, and can potentially attack the one that infected them. Additionally, only humans can become vampires, whereas the Acute Zombie Powder can affect any kind of animal and even some plants.
  • Weakened by the Light: Vampires burn up in sunlight, though the process isn't instant, which gives some time to get to shade. Interestingly, in Volume 3 it's acknowledged that this isn't consistent with folklore or works such as Dracula.
  • We Have Reserves:
    • Erika and Ayumi take this approach with their vampire and zombie minions, as they can always make more. Of the two, Erika is by far the more extreme example. She has a group of vampire minions form a parasol with their bodies (causing them to constantly burn up and require replacement), defeats Ayumi's animal zombies by letting her minions get eaten by them (again, in direct sunlight), and has them block off a flood by literally clogging up the street with their bodies.
    • With the ability to split himself into multiple bodies, Satori takes this approach with himself. He sends several of his bodies to their deaths just to keep an enemy occupied, and keeps several other bodies hidden as a safety measure.
  • Wham Line:
    • Volume 2 has two examples in quick succession.
    "Even if [Satori] is your son, I strongly recommend making a decision about him sooner rather than later."
    "Archenemy Lilith, aka Amatsu Yurina."
  • The Worf Effect:
    • When Karen reveals her true power, she easily beats up Satori, Helen and Yukie, and takes out Tamago when he tries to intervene.
    • In her first appearance, Lilith toys around with the Amatsu siblings like they were children, though she's taken out by a surprise attack.
  • Zombie Apocalypse: A virtual example in the very first volume. Even animals get in on the action, making it look like something out of Resident Evil.

Alternative Title(s): My Vampire Older Sister And Zombie Little Sister


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