Hayato Kisaragi

The male protagonist of Hundred. Originally from Yamato, Hayato became a Slayer in order to obtain state-of-the-art medical treatment for his sister.
- Accidental Pervert: As standard for any harem protagonist. He ends up in a lot of suggestive positions with women in his harem and beyond.
- Amnesiac Hero: Had a lot of his memories erased from when he was a kid.
- Babies Ever After: The light novel series ends with the introduction of Emilia and Hayato's children, a son and daughter.
- David vs. Goliath: Hayato has only had his Hundred for two days and he has to fight against Claire who's considered the best Slayer in the academy.
- First-Name Basis: Sakura insists that Hayato call her by her first name. When he starts casually mentioning it to the other girls, such as Claire and Emil, both of them get rather upset that he's apparently already friendly enough with her to do this, while they're still on a more professional Last-Name Basis with him.
- Forgotten First Meeting: With Sakura. She originally met Hayato and Karen at a shelter in Gudenberg but Hayato doesn't remember it.
- Harem-Powered: The trope is Played With, in that Hayato gains a Power Limiter through his harem because he's a "Variant"a Half-Human Hybrid caused by his DNA being infected with the Savage virus. Using too much of his Variant power can cause him to go berserk, unless the Savage virus is put under control. He can do this by "giving" some of the virus to someone else, via a kiss. If the person wasn't already a Variant themselves, they will become one by kissing him. In addition to this, two other women in his harem (Sakura and his little sister Karen) can also calm out-of-control Variants with their music.
- Heroes Prefer Swords: Trained in kendo and his Hundred comes with a sword.
- Instant Expert: After a mere two days of owning a Hundred and Hayato can already use its full body armament and deploy an n-barrier, things not a lot students know how to do. He overwhelms and nearly defeats Claire, who's considered the strongest Slayer in the academy. Granted, he was definitely not himself while doing those things.
- Mistaken for Gay: Emilia is very clingy toward Hayato. Hayato is largely indifferent about it but from an outsider perspective they look like a couple. Karen even asks Hayato if he's interested in guys.
- New Old Flame: With Sakura.
- Nice Job Breaking It, Hero!: Had Hayato just met the two girls who were waiting for him at the airport, he could've avoided the mishap with Claire trying to expel them for failing to bring him to the school.
- Oblivious to Love: Several of the girls are interested in Hayato, but naturally he's too dense to realize it.
- In the anime at least, he definitely realizes it, but wants to focus on getting his sister healthy. Plus, he's more than a little uncomfortable and unsure.
- Red Eyes, Take Warning: He has red-ish eyes and while he's not evil, he does have a Superpowered Evil Side that basically has him go in full Berserk Mode.
- Suggestive Collision: Less than a second into his duel with Claire and Hayato crashes right on top of her and even accidentally gropes her.
- Superpowered Evil Side: During Hayato's duel with Claire something inside him snaps causing his eyes to yellow, and become much more proficient and ruthless with his hundred. It is later explained that he was exposed to Savage blood when he was a kid, increasing his Hundred score. With help from Emilia, he learns to control it.
- Thanks for the Mammary: After crashing into Claire, Hayato tries to get off of her only to accidentally grope her chest.
- Training from Hell: Hayato doesn't have a lot of time to be eased in with his hundred before his duel with Claire so Emil just goes all out on him to force him into becoming used to it.
- Trial by Combat: Claire challenges Hayato to a duel where if he wins she'll revoke her order to have two girls and Emilia expelled.
- Unskilled, but Strong: Hayato has a high Hundred aptitude thanks to having Variant viruses, but is a complete novice at using it, though he learns quickly enough to at least fight alongside his seniors.
- Unwanted Harem: Whether he likes it or not, Hayato has a lot of girls interested in him.
- Unwitting Instigator of Doom: After landing on little garden Hayato was supposed to be escorted to the academy by two other students but the way they called out for him was a little embarrassing so he sneaks pass them and goes to the academy by himself. This causes them to be late for Claire's speech and nearly expelled.
Emilia Crossfode

The female protagonist of Hundred. She is a silver-haired girl from the Britannia Empire and Hayato's roommate.
- Babies Ever After: The light novel series ends with the introduction of Emilia and Hayato's children, a son and daughter.
- Childhood Friend Romance: Sakura and Emile are arguing over who has the better rights to this until Karen one ups them by pointing out she has known Hayato all her life.
- Clingy Jealous Girl: Emilia gets rather upset any time Hayato is spending time with another girl. Or if another girl shows interest in him.
- Clothing Damage: Emil suffers this in episode three, which also doubles as an Unsettling Gender Reveal to Hayato, who thought she was a boy up until this point.
- First Girl Wins: Hayato ends up with Emilia, who was the first girl he met both in the past and at the academy.
- Godiva Hair: Has hair long enough to cover her nipples.
- Magic Kiss: Emilia does this with Hayato throughout the series as kissing can apparently transfer active or inactive Variant viruses to people; the active version gives Slayers a power boost, while the latter can stabilize them if their Variant powers go out of control.
- Morph Weapon: Emilia's Hundred can change into many weapons from lance, swords, cannons.
- Mystical White Hair
- Pervert Revenge Mode: Hayato walks into his dorm room unaware that Emilia is his roommate. When he sees her with just a towel on, Emilia gets flustered and throws among other things, a suitcase at him.
- Rescue Romance: When they were children, Hayato saved Emilia from a Savage, which caused her to develop a crush on him.
- Sweet Polly Oliver: For some reason Emilia has to disguise herself as a boy.
Claire Harvey

The highest-ranked Slayer in Little Garden who is from the United States of Liberia, she is called the Queen.
- Absurdly Powerful Student Council: She immediately orders the expulsion of two girls who were supposed to pick up Hayato at the airport, but failed because he hid from them. When Emilia protests, Claire says that in battle, an order not obeyed could have fatal consequences. Hayato is then forced to duel her in order to spare the girls' expulsion order.
- Also justified as the Student Council are "Selections," who are employed by the U.N. to hunt down Savages.
- Alpha Bitch: Perhaps a bit downplayed. She has her two Beta Bitch sidekicks in Liddy and Erica, she's called the "Queen", and didn't hesitate to order the expulsion of three students, but she's not portrayed as being outright unbearable.
- Asskicking Equals Authority: She's the student council president and the highest ranked Slayer in Little Garden.
- Beam Spam: Claire is capable of this thanks to having multiple guns on her Hundred suit.
- BFG: Claire's multiple guns can combine into a large one.
- Boobs of Steel: She's the strongest fighter at Little Garden, and has a huge rack.
- Bridal Carry: Hayato flies off with her like this in episode 3 when he pulls her out of the face of danger. With a second incident of Thanks for the Mammary to go with it. She even lampshades it later saying how "it was her first princess carry."
- Clingy Jealous Girl: She has her moments.
- Disproportionate Retribution: She nearly expels two girls for being late for her entrance speech. Her justification being that mistakes no matter how small should not be tolerated in the academy because on the battlefield even a small mistake could be fatal.
- Disqualification-Induced Victory: A variant that results in a tie rather than a victory. Although Claire defeated Hayato in their match, due to his Superpowered Evil Side taking form, she self-admits that she violated the rules she set for herself to do it.
- Gorgeous Gaijin: Coming from a county called "United States of Liberia" kind of gives to the fact that she's probably supposed to be American.
- Let's Fight Like Gentlemen: Since Hayato has barely any experience with a Hundred, for their duel Claire promises not to use her full body armament and allows Emilia to help him.
- Mega Twintails
- Ms. Fanservice: Oh so very much. She has a well-endowed body that Hayato often finds himself landing on top of and gets a topless pool and beach scene alongside a scene of her relaxing naked in a lake.
- Rapunzel Hair: Her twintails go past her back in length.
- Rescue Romance: After Hayato saves her from a Savage and, later, accidentally kisses her, she falls in love with him.
- Noblesse Oblige: While she's not royalty, she is student council president and even says that "those with power must defend those that don't".
- Pervert Revenge Mode: Twice:
- In his duel with Claire he accidentally gropes her causing her to lose her cool with him.
- When Claire is sunbathing and forgets that her top is undone, she sits up and accidentally flashes him. In this case, it is her two underlings who attack the poor guy.
- Shower Scene: In Volume 11, Claire takes a shower while remembering the times Hayato has groped her.
- Single Woman Seeks Good Man
- Willfully Weak: For her duel with Hayato, Claire states she will not to use her full body armament as that would end the fight in seconds. Proven true after the duel starts to turn in Hayato's favor and she had no choice but to use it which wins her the duel.
Karen Kisaragi

Hayato's younger sister who is ill.
- Alliterative Name: Karen Kisaragi
- Childhood Friend Romance: Sakura and Emile are arguing over who has the better rights to this until Karen one ups them by pointing out she has known Hayato all her life.
- Clingy Jealous Girl: There but subtle.
- Hime Cut: Her hairstyle.
- Ill Girl: The main reason Hayato wants to be a slayer is so he can get money to take care of his sister, Karen, who is suffering from a disease that requires her to be hospitalized and wheelchair-bound.
- Seers: While staying in the hospital she is often seen playing tarot cards, where she has become sort of a clairvoyant.
Sakura Kirishima

A popular idol who falls in love with Hayato after seeing him defeat the Trenta Savage at Zwei Island.
- Absolute Cleavage: In this
◊ outfit.
- Anti-Gravity Clothing: Those sleeves of hers certainly defy the laws of gravity.
- Bathing Beauty: Opening of episode 4 shows her taking a shower.
- Bodyguard Crush: She hired Hayato to be her bodyguard for her concert.
- Cherry Blossom Girl: Has pink hair, named Sakura, and is a love interest. Also a Pink Color Motif.
- Childhood Friend Romance: Sakura and Emile are arguing over who has the better rights to this until Karen one ups them by pointing out she has known Hayato all her life.
- Clingy Jealous Girl: Has her moments.
- Curtains Match the Window: Purple-pink hair and eyes.
- First-Name Basis: Sakura insists that Hayato call her by her first name. When he starts casually mentioning it to the other girls, such as Claire and Emilia, both of them get rather upset that he's apparently already friendly enough with her to do this, while they're still on a more professional Last-Name Basis with him.
- Floral Theme Naming: Sakura means "cherry blossom".
- Forgotten First Meeting: With Hayato. She remembers meeting him and Karen but she never learns his name until they finally meet again. He in turn couldn't remember her because his memories were erased.
- Girlish Pigtails: And two very long ones at that.
- Hand-Hiding Sleeves: Of the High-Class Sleeves variant.
- Idol Singer
- Instrument of Murder: Her voice. Her singing can calm down rogue Variants.
- Ojou: She's a very popular Idol Singer.
- Parental Abandonment: Her father sold her to Warslran Research Facility after falling ill and her mother is never really mentioned.
- Rapunzel Hair: Her tails almost reach her knees.
- Rose-Haired Sweetie: Clingy Jealous Girl aside, she's actually very nice.
- Sole Survivor: She is the only one of the test subjects to have survived after being sold to the Warslran Research Facility.
- Support Party Member: Can't fight. Instead, she uses her singing to calm down out-of-control Variants.
- Wacky Marriage Proposal: Sakura proposes a marriage to Hayato once they're alone in her hotel room, mostly because of the fame surrounding him after defeating a Savage. He's naturally hesitant, but goes with the flow anyway, which then throws her off as she was probably just teasing him, and didn't expect a serious answer.
- Unwitting Test Subject: Her father sells her to the Warslran Research Facility after becoming ill.
- You Gotta Have Blue Hair: Pink hair.
Liddy Steinberg

Little Garden's student council Vice President who is in charge of enforcement, she is very loyal to Claire and can be very uptight when enforcing the school's rules and regulations.
- Beta Bitch: Towards Claire.
- By-the-Book Cop: Can be very uptight when enforcing the school's rules and regulations.
- Clingy Jealous Girl: Towards Claire.
- Curtains Match the Window: Teal hair and eyes.
- Jousting Lance: Her Hundred takes the form of a lance and a shield.
Erica Candle

She is also student council Vice President, however, she is mostly in charge of strategic planning, she has a high admiration for Claire, and it is suggested that she has certain feelings for her.
- Beta Bitch: Towards Claire.
- Clingy Jealous Girl: Towards Claire.
- Epic Flail: Her Hundred takes the form of a massive chained yoyo that she uses for restraining.
- Incompatible Orientation: It's suggested she has feelings for Claire, however, there is no evidence suggesting that Claire is into girls.
- Meganekko
- Schoolgirl Lesbians: Has unrequited feelings for Claire.
- The Strategist: Considering her position on the student council.
Fritz Granz

Hayato's classmate and Reitia's partner. His Hundred takes the form of a sniper rifle.
- Beta Couple: With Reitia.
- Childhood Friends: With Reitia
- Guys Smash, Girls Shoot: Inverted since Fritz serves as the sniper while Reitia is the close range fighter.
- Huge Guy, Tiny Girl: With Reitia.
Reitia Saintemilion

She is classmates with Hayato and Emilia, she is also Fritz's partner.
- Beta Couple: With Fritz.
- Childhood Friends: With Fritz.
- Cute Little Fangs: Has 2 of them.
- Huge Guy, Tiny Girl: With Fritz.
- Guys Smash, Girls Shoot: Inverted since Fritz serves as the sniper while Reitia is the close range fighter.
- Nobody Touches the Hair: Doesn't like being patted on the head.
- Pint-Sized Powerhouse
- Spell My Name with an "S": Her name gets spelled as both Reitia and Latia. Not to mention her surname gets spelled in about 10 million different ways.
- Tomboyish Ponytail
Charlotte Dimandias

She is a child prodigy who serves as the Little Garden's only main technical expert and chief researcher on Hundreds.
- Child Prodigy
- Emotionless Girl: Tends to speak in a very calm and monotone voice.
- Improbable Age: She's the academy's chief researcher of Hundreds with a doctorate under her belt yet doesn't seem to be out of middle school.
- Labcoat of Science and Medicine: Always seen wearing a labcoat basically being a scientist and all.
- Meganekko
- Smart People Wear Glasses: Considering her position.
- Token Mini-Moe
- You Gotta Have Blue Hair: Purple hair.
Miharu Kashiwagi

Miharu is a nurse at the hospital where Karen is staying.
- Gag Boobs: The first shot of Miharu, a nurse assigned to take Karen, is of her huge breasts. Hayato gets extremely flustered at the sight of them.
- Hospital Hottie: She's a nurse with a huge rack.
Nesat Olfred

One of the three Hunters that have Variant powers injected into them by Vitaly.
- Curtains Match the Window: Black hair and eyes.
- Dragon Their Feet: The Olfred siblings continue attacking Little Garden even after Vitaly is already taken care of by Judal. Thankfully, however, they manage to make a HeelFace Turn through Hayato.
- Eyepatch of Power
- Made a Slave: She along with his other siblings were originally orphans who were slaves and treated brutally.
- Redemption Demotion: Although free from Vitalys control, the Olfred siblings only regain 80% of their original power.
- Unwitting Test Subject: Made into one by Vitaly.
Nakri Olfred

One of the three Hunters that have Variant powers injected into them by Vitaly.
- Dragon Their Feet: The Olfred siblings continue attacking Little Garden even after Vitaly is already taken care of by Judal. Thankfully, however, they manage to make a HeelFace Turn through Hayato.
- Made a Slave: She along with his other siblings were originally orphans who were slaves and treated brutally.
- Redemption Demotion: Although free from Vitalys control, the Olfred siblings only regain 80% of their original power.
- Unwitting Test Subject: Made into one by Vitaly.
Krovanh Olfred

- Curtains Match the Window: Black hair and eyes.
- Dragon Their Feet: The Olfred siblings continue attacking Little Garden even after Vitaly is already taken care of by Judal. Thankfully, however, they manage to make a HeelFace Turn through Hayato.
- Made a Slave: He along with his other siblings were originally orphans who were slaves and treated brutally.
- Redemption Demotion: Although free from Vitalys control, the Olfred siblings only regain 80% of their original power.
- Straw Nihilist: Him being treated brutally causes him to hate the world.
- Unwitting Test Subject: Made into one by Vitaly.
Vitaly Tynyanov

One of the main antagonists of the series. She was originally a member of the Warslan Research Facility, allowing her to gain much access to the data of the Little Garden and have much knowledge about the technologies.
- Absolute Cleavage: She probably needs to go up a shirt size with that rack.
- Arc Villain: She manipulated the Olfred siblings into gathering Savage cores and Variable Stones for her so she can use them to build a biomechanical army to attack Little Garden. However, she dies at the end of the season, which doesn't cover the entire series, thus disqualifying her for Big Bad status.
- Curtains Match the Window: Eyes and hair appear to be the same color.
- Evil Redhead: Or at least some kind of burgundy-esque color.
- Gender-Blender Name: Vitaly is a boys name and if she's supposed to be Russian, Tynyanov is the masculine version of the surname. For women it should be Tynyanova. A woman with a masculine name and surname at that.
- Mad Scientist: Considering how she treats her test subjects.
- Red Eyes, Take Warning: If burgundy counts then yes.
- Woman Scorned: Vitaly attacks Little Garden out of spite for Judal, who used her for his own ambitions and threw her away.
Claudia Lowetti

Emilia's friend from Gudenburg. She is very protective of Emilia and heartily wishes for her to come home with her.
- Ojou Ringlets: Unknown if she's of high social status but features two somewhat toned down ringlets.
- Psycho Lesbian: Down Played with Emilia's Unlucky Childhood Friend Claudia who is a bit obsessed but mostly harmless.
- Shipper with an Agenda: Claudia tries to get Hayato alone with Claire so that she can have Emilia to herself.
Meimei

- Animal-Eared Headband: A headband with cat ears.
- Cleavage Window
- Genki Girl: Very energetic and upbeat.
- Lolita Fashion
- Pimped-Out Dress: More of a puffy skirt but still counts.