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The Kouga Clan
Kouga DanjouThe old leader of the Kouga clan, and grandfather of Gennosuke. He used to be in love with lady Ogen. Seems to be skilled at using poisoned needles. Gets impaled in the chest by Ogen, making him the first ninja to die.
- Combat Pragmatist: Attacks Lady Ogen without warning as soon as she turns her back on him, right after the former Shogun announces the contest between the ten ninja representatives from each clan.
- Hoist by His Own Petard: Ogen use one of the large needles thrown at her to stab him through the heart.
- I Was Quite a Looker: While not a super bishonen, he was quite Tall, Dark and Handsome in the past
- Improbable Weapon User: Very large needles. Implied to be poisoned.
- Star-Crossed Lovers: With Ogen, decades ago.
- Together in Death: With Ogen.
Voiced by: Kosuke ToriumiDanjo's heir and strongest member of the Kouga ninja. He's a peace-loving idealist who's genuinely in love with Oboro and wants to put an end to years of hate and rivalry. His special power is a "Do Jutsu" (Fierce Ability) in his eyes, that allows him to send an attacker's killing intent back at him. Commits suicide after witnessing Oboro's suicide. He is the very last of the twenty ninjas to die.
- Big Ol' Eyebrows: A trait he takes from his grandpa.
- Bishōnen: Thanks to his long, lush eyelashes and hair.
- Death Glare: Literally! His Do Jutsu allows him to reverse an assailant's killing intent and force them to commit suicide. He also looks very livid when using this power.
- The Dreaded: And for good reason.
- Driven to Suicide: After witnessing Oboro's death in his own arms he declares the Iga as winners, takes Oboro's body with him and commits Seppuku in a river.
- Handicapped Badass: Even after being blinded by the Seven Days potion he can still fight and slay Tenzen with ease.
- Heterosexual Life-Partners: With Jousuke.
- Karmic Death: Weaponized, as he inflicts one on his enemies using his Dojutsu.
- Love at First Sight: For Oboro.
- Master Swordsman: Carries a katana with him, and even when blinded he manages to behead Tenzen with ease.
- Nice Guy: Is very peaceful and reasonable. Considering that he can kill you with a glare, that's a positive thing.
- Red Eyes, Take Warning: Let alone crimson with golden irises ...
Kazamachi ShougenA hunchbacked spidery-looking man, he's the first Kouga Ninja shown alongside Danjo. Can spit a web-like phlegm that's stronger than glue, and secrete chemicals from his hands and feet that let him move along his "webbing" without getting stuck. He's ambushed by the Iga ninja and finished off by Hotarubi. This makes him the third ninja to die. A near carbon-copy of Kazamachi appears during the Iga's "visit" to the Kouga village, distinguishable only by the fact he lacks Kazamachi's missing upper teeth.
- Animal Motifs: Spider, of course.
- Arachnid Appearance and Attire: The combination of his spindly limbs, tendency to get around on all fours, bulbous hunchback, and brow studs makes him look a lot like a giant spider.
- Defiant to the End: When Hotarubi tries to force him to confess all he knows, he spits on her cheek. And he gets 'nightmarishly stabbed for his trouble.
- Gonk: Ugly of face, hunched of back, with teeth knocked out to let his grotesque tongue protrude and six crimson studs embedded in his brows in two vertical rows of three, which furthers his resemblance to a spider.
- Mundane Utility: In a flashback he's shown using his web spit to nail the fish he's catching to a rock.
- Overly Long Tongue: Which he uses to better direct his web spit. In the anime, some scenes even imply he unleashes his spittle from it, like a tube.
Udono JousukeA fat, jolly ninja who's often seen near Gennosuke. Despite looking like a moron, he's very competent and quite smarter than he looks. His body is like a rubber balloon, making him able to squeeze through small openings, absorb physical impacts without harm, or expand his body to become a living ball that can propel itself super-high into the air or roll at high speeds along the ground. Is killed by Jingoro, who forces himself down his gullet while in slug form. This makes him the fifth ninja to die.
- Acrofatic: Because his "balloon technique" lets him inflate himself like a balloon, he can leap incredibly high, and move with incredible speed by rolling around.
- Big Fun: Very pudgy, but also a lecherous, crude, good-hearted party animal.
- Casanova Wannabe: He attempts to woo Akeginu with hamfisted and crude come-ons, and in a flashback episode is shown groping Okoi, with dialogue implying this is far from unusual for him.
- Crouching Moron, Hidden Badass: There's a reason why Gennosuke trusts him.
- Distracted by the Sexy: He tries to stop Gennosuke from accepting the invitation to the Iga village, but stops as soon as Akeginu politely asks him to come as well.
- Fat Idiot: Subverted, he intentionally behaves as one to catch his opponents offguard.
- Heterosexual Life-Partners: With Gennosuke.
- Lightning Bruiser: He's extremely fast and nimble despite his size.
- Rubber Man: His body is like a rubber balloon.
Jimushi JuubeiOne of the more mysterious and grotesque members, he's a limbless man who serves his clan as an astromancer and seer. Though he has no arm nor legs, but can fight with an extremely long prehensile tongue and a knife hidden in his throat. His scale armor allows him to crawl around really fast like a snake. He kills Tenzen for the first time, but is cornered by the latter after resurrecting, and is promptly bifurcated by Tenzen. This makes him the fourth ninja to die.
- Animal Motifs: Snakes.
- The Grotesque: His features aren't so ugly, but he's physically deformed in the "human torso" style — he has no arms or legs, just a head atop a torso. This forces him to be carried or crawl everywhere.
- Handicapped Badass:
- Yup, just because he doesn't have limbs that doesn't mean that he can't kick your ass. Tenzen learnt it the hard way.
- In the Novel, He's "just" quadriplegic, but can still regurgitate blades at high speed and turn his skin in a scaly, hard hide.
- Knife Nut: Hidden down his esophagus, though it is called a "spear" In-Universe.
- Meaningful Name: Jimushi means "Earth Insect". Look at him when he crawls on the ground, moving like a centipede.
- Oh Crap!: Sadly he didn't know about Tenzen's resurrecting skills.
- Overly Long Tongue: His only weapon. Though considering how freaking skilled he is in using it to replace his limbs...
Voiced by: Yoji UedaMember of the Kouga Ninja he's a short and sneaky guy whose eyes are always shut. He's Okoi's older brother. His powers allow him to transform into anyone, simulate voices and even change his size. He's eventually tricked by Tenzen and killed by the soldiers escorting the Iga ninja.
- Beware the Nice Ones: Despite his docile looks, this is the same dude who slices Hotarubi's arms off and then proceeds to impale her.
- Big Brother Instinct: Towards Okoi. When she died, all bets were off in regards to him. Certainly explains the horrible way in which he killed Hotarubi, when not even a single hour had passed.
- Eyes Always Shut: He opens them only when experiencing strong emotions.
- Impaled with Extreme Prejudice: By several spears no less.
- Manipulative Bastard: Can be very sly and sneaky. Especially seen when he imitates Akeginu's voice to confuse Koshirou and allow Kagerou to give him a Kiss of Death.
- Master of Disguise: He can turn into anyone at will by taking a model of their face from a mud mask. It's stated that he can even change his height, but for some reasons he can't copy the nostril's hair.
- Nice Guy: When off duty, he's rather reasonable and not a bad dude. Once he's your opponent, however, you're fucked..
- The anime noticeably made him less ruthless and more sympathetic.
- Oh Crap!: When Oboro's eyes disband his perfect disguise as Yashamaru and much later, (while disguised as Tenzen) when the soldiers (and Tenzen among them) reveal that Tenzen's powers involve coming back from the dead.
- Pet the Dog: In the manga, he briefly turns into Yashamaru to comfort Hotarubi as she's dying. In the anime, he simply says "yes" when she hallucinates he is Yashamaru whilst dying.
- The Stoic
- Tiny Guy, Huge Girl: He's the tiny guy to his sister's huge girl.
Muroga HyoumaA good friend of Saemon and Danjo's advisor. He's Gennosuke's maternal uncle and he taught him everything he knows, including the Dojutsu. He appears to be blind and has an excellent hearing but he can actually use the dojutsu, but only by night. Gets killed by Koshirou, since being blind he's able to work around the Doujutsu's only weakness.
- Death Glare: Literally! Just like Gennosuke, albeit always active.
- Died Standing Up: Against Koshirou, driving him mad as he can't determine if his opponent is dead or not.
- Handicapped Badass: The man has severe eyesight problems, though the exact source and effects vary per media. In any case, he's still not to be trifled with.
- Power Incontinence: His Dojutsu is constantly active, so he has to keep his eyes shut and essentially render himself blind in order to keep from killing others accidentally, only ever opening them when instructed to by his allies.
- Parental Substitute: Helped raise Gennosuke after the death of his older sister aka Gennosuke's mom.
Kasumi GyoubuA large and massive ninja of Kouga. Always seen around Hyouma and Saemon. He's very strong and can merge with any solid surface, allowing him to move around unseen. As a child he was traumatized by his father's death and shaved his head because of that. He's impaled by Tenzen while trying to flee from him and his corpse is merged inside a wooden panel, exhibited as a warning to the Kougas. He is the twelth ninja to die.
- Big Damn Heroes: First when he saves Saemon from Yashamaru. Later, when he stops Tenzen from raping Oboro by snapping his neck. (Didn't likely intend to save Oboro, but whatever).
- Full-Frontal Assault: Dude must strip to use his powers. Guess what happens.
- Genius Bruiser: Large and massive but also quite smart.
- Gonk: The fact that he must be nude to use his ninja skills doesn't help.
- Leeroy Jenkins: At one point he decides to leave the main group despite Gennosuke's plans and directly go for the Iga ninja.
- He might have pulled it off, too, if not for Tenzen's resurrection powers, and the accidental death of an innocent father.
- My God, What Have I Done?: In the anime, he's horrified when he mistakenly kills the flautist father in front of everyone, including his kid. The fact that his dad's death was his own Start of Darkness doesn't help. And it gets worse as his shock over that is what lets Tenzen kill him.
- Odd Friendship: In the anime he gets along pretty well with Okoi, and they're even shown hunting boars together.
- Used to Be a Sweet Kid: Young Gyoubu, as per the anime, was a very sweet child. Then his father died...
OkoiOne of the two kunoichi of Kouga, she's Saemon's little sister. She's a large, well muscled girl who a tomboy, but she's ready to take advantage of her large breasts if needed. She's a human-leech who can drain people's blood from her skin, causing also physical pain. She gets captured and tortured by the Iga clan, and though she manages to kill Azuki in the process, she is eventually is killed by Nenki while trying to escape. This makes her the eighth ninja to die.
- Amazonian Beauty: Very tall. Very muscle-bound. Very beautiful.
- Animal Motifs: Leeches.
- Badass in Distress: The Iga clan capture her and torture her. This doesn't stop her from killing Rosai and almost doing the same to Jingoro and Nenki. If only Nenki had not been able to counterattack.
- Boobs of Steel: Amongst the Kouga Ninja she's the strongest female character and also the bustiest.
- Dark Action Girl: Considering her powers...
- Gag Lips: Very accentuated in the manga. Justified when you think of her blood draining powers.
- Human Pincushion: Gets impaled by Nenki's hair and turned into this.
- I Surrender, Suckers: Pretends to be wounded, defenseless and totally unable to fight back with Jingoro, in order to catch him offguard and suck his blood.
- Odd Friendship: With Juubei (the two are tea-time buddies, so she says) and Gyoubu (with whom she often goes boar-hunting).
- Plucky Girl: She will never EVER give up on anything she wants or needs. Even when she's about to kick it, she manages to tell Saemon where's the scroll in her last words.
- Sibling Yin-Yang: Okoi is a tomboyish Boisterous Bruiser. Saemon is a calm Master of Disguise.
- Stripperiffic: Again, justified as she needs to touch someone with her bare skin to suck his blood.
- Tiny Guy, Huge Girl: She's far taller than her brother.
Voiced by: Risa HayamizuThe other kunoichi of the Kouga clan. She's a feminine woman with black hair and red lips, madly in love with Gennosuke and vehemently jealous of Oboro. When she's aroused, her breath becomes a poisonous miasma. She's horrifically raped and tortured with needles by Tenzen, which breaks her even further.
- Adaptational Villainy: The anime makes her a full-blown yandere.
- Angst: Given her powers, this is pretty justified.
- Blessed with Suck: Big time. In the anime, at least, she can't even kiss someone she's sincerely attracted to without starting to kill them. In the anime continuity, dialogue amongst the other Kouga implies that this is a family trait, and eventually they're going to need to breed her in order to create a daughter to take her place, something that they note will doubtlessly kill many men before she conceives.
- Bodyguard Crush: For Gennosuke.
- Break the Cutie: While Oboro is the "champion" for this trope, Kagerou follows suit.
- Clingy Jealous Girl: She hates Oboro and wishes to kill her with her own hands. Far more accentuated in the anime, though, where she reaches Yandere extremes.
- Death by Sex: Weaponized, as she inflicts this on anyone who's fool enough to lay with her. Except Tenzen, who's resurrected by his powers.
- Femme Fatale: Her special ninja skill is based on this; she seduces men into bedding her, then kills them with the poison she excretes from her mouth and skin during carnal intimacy.
- Go Out with a Smile: As she's about to die, Oboro looks at her and nullifies her powers, allowing her to die close to Gennosuke's face.
- Meaningful Name: "Kagerou" means "Heat Wave", but can also refer to the Mayfly.
The Iga Clan
Voiced by: Hisako KyodaThe old leader of the Iga clan, she used to be in love with Danjou. Her powers are unknown but she seems to have a tamed falcon as a pet. She's the second person to die in the series, killed by Danjou's needles. Though not before she takes him with her.
- Brutal Honesty: When informing Oboro that she's far too clumsy to be a ninja. (Though she's not as harsh in the anime.)
- I Was Quite a Looker: As a young woman, she was very pretty.
- Made of Iron: Survived to a needle that went throught her mouth and neck long enough to pull it out and use it to kill Danjou.
- Star-Crossed Lovers: With Danjou. They were supposed to be the ones getting married to end the rivalry.
Iga-no-OboroOgen's granddaughter and Gennosuke's soon-to-be wife. She's a very sweet and clumsy person. She can't fight, but her eyes have the power of cancelling any ninja power or technique seen, which is considered as one of the most deadly powers in the whole series. After going through a long series of Break the Cutie moments she kills herself in order to allow Gennosuke to win.
- Anti-Magic: Her "Piercing Eyes" are basically this, and are mentioned to be the deadliest power ever among both clans.
- The Chick: Even more when she willingly blinds herself with the seven days potion to not use her skills against her own people.
- Cursed with Awesome: How many of the other ninjas see her. Girl cannot fight at all and yet she has the potentially deadliest power.
- Cute Clumsy Girl: Pointed out by her own grandmother too. And not Played for Laughs.
- Driven to Suicide: She cannot bring herself to kill Gennosuke in the final showdown, so she kills herself.
- Spanner in the Works: Four times, actually. First, she disrupts Chikuma's powers during his attempted duel with Gennosuke, resulting in his Razor Wind ripping out his eyes. Then she seals her own Anti-Magic eyes with the Seven Days Ointment so she won't be tempted to use them against her own clansmen — also making impossible for Tenzen to use her against others. Later, she's vital into killing Tenzen himself when her eyes are unsealed right when he's reviving himself after being defeated by Gennosue. And last but not least, her Heroic Suicide derails Ofuku's own gambits, sending her into a mighty Villainous Breakdown.
- Take a Third Option: Torn between killing Gennosuke or allowing him to kill her, she chose this.
- What the Hell, Hero?: Calls Akeginu out when she violently maims Hyouma's body.
Voiced by: Naoki YanagiThe first Iga ninja shown along with Ogen. He's a pretty boy who can use the hair of deceased women, treated with animal oils, as deadly garrot wires. He's Hotarubi's boyfriend. He's killed by Gyoubu, making him the seventh ninja to die.
- Bishōnen: Described in the novel as having "cherry blossom cheeks and shiny black eyes."
- Neck Snap: How Gyoubu kills him.
- Nice Guy: He's one of the few ninjas who doesn't really enjoy fighting and prefers to live peacefully with Hotarubi.
- Razor Floss: Made from the hair of deceased women bathed in a special oil. In the novel, it was a single rope.
- Traumatic Haircut: During the battle against Shogen, his long black hair gets hacked off by his own weapon.
Voiced by: Show HayamiA very high-ranked Iga ninja serving Ogen, he's one of the strongest members, and surely one of the most evil characters in the manga, and that's saying something. He's the mastermind behind the Iga-Kouga war. Has an unhealthy attraction for Oboro. Thanks to a parasitic twin living in his body he can come Back from the Dead at will. Is eventually beheaded by Gennosuke and destroyed when Oboro use her Anti-Magic on the parasite twin while at work, thus nullifying his powers.
- Adaptation Expansion: In the manga, his parasite is identified as his younger twin brother, while in the anime the parasite is the ghost of Tenzen's mother, killed long ago by his father, and now manipulating her son for revenge.
- Adaptational Badass: In the manga and novel, he trips over a broken board and only inflicts superficial injuries on Gennosuke before being decapitated. In the anime, he matches Gennosuke blow-for-blow and inflicts several serious injuries on his opponent.
- Asshole Victim: After all of the atrocities he committed, up to and including kick-starting the Iga-Kouga war and trying to rape Oboro twice, Tenzen more than had it coming when Oboro killed him.
- Attempted Rape: Twice on Oboro and also on Kagerou.
- Ax-Crazy: During his fight with Gennosuke.
- Back from the Dead: He was born with a parasitic twin inside his body. Said twin is normally seen as a small bulge on his ear. If Tenzen's killed, the twin reach the wound and "eat it", allowing Tenzen to raise from the dead.
- Big Bad: Surely he's the most suitable character for the job.
- Body Horror: How his resurrection works. This gets disgustingly bad the last time, when you see the parasite using Tenzen's sliced neck as a mouth to speak.
- Break the Haughty: As Oboro's eyes finally kill him, all of his sanity completely snaps.
- The Chessmaster: He's the mastermind behind the new conflict.
- Dual Wielding: In the film, he carries around and uses two chakrams.
- Dude Looks Like a Lady: In the novel, he even sports purple lips.
- Impaled with Extreme Prejudice: His first death, courtesy of Jubei. He makes sure Saemon is at the receiving end as well.
- Manipulative Bastard: The Iga-Kouga war can be laid at the feet of his machinations.
- Neck Snap: His second death, done by Gyoubu.
- Off with His Head!: His fourth and final death.
- Politically Incorrect Villain: According to him, the best and only way to submit a woman, is to rape her. He also firmly believes Rape Is Love and so attempts to "convince" Oboro to turn away from Gennosuke by raping her.
- Sadist: He really loves making his enemies feel pain.
- Smug Snake: Would've been a Magnificent Bastard, and some of his plans were pretty good... but his unnecessary sadism and his MASSIVE arrogance are huge drawbacks; he gets himself killed several times over.
- Stalker with a Crush: Towards Oboro.
- Who Wants to Live Forever?: Many people would consider immortality quite awesome, though in the anime he affirms that he has lived for so long and has been resurrected so many times that for him, immortality is the worst of curses.
- Your Head Asplode: That's what happens when Oboro nullifies his Back from the Dead powers.
Azuki RousaiAn old shinobi who can stretch his limbs and neck like boneless tentacles. He's grumpy and easy to anger. Meets his doom in Okoi's arms during an attempt at interrogating her. This makes him the sixth ninja to die.
- Animal Motifs: His elongated skull and his tentacle-like limbs can make you think of a squid.
- Badass Grandpa: Shown to be strong enough to smash a stone wall to pieces with a kick.
- Cruel and Unusual Death: Okoi manages to hug him and suck all his blood, turning him in a dried up mummy.
- Death by Irony When he tries to hit Okoi... he gets his blood sucked out.
- Mundane Utility: He and Nenki take advantage of their own gonkiness to try to scare the hiccup away from Oboro.
- Rubber Man: Can stretch his limbs and neck. Josuke even calls him a "Rubber monster".
- Would Hit a Girl: When questioning Okoi, he threatens to rip off her limbs and breasts should she refuse to answer.
Voiced by: Kenji UtsumiAn odd-looking shinobi with very long and messy hair, huge eyebrows and long nose hairs. He can animate and control all the hairs of his body and can use a long staff. Hyouma use his dojutsu on him, causing him to break all his own bones. This makes him the ninth ninja to die.
- Animal Motifs: It's subtle, but the sheer hairiness of his body, his fondness for wielding a staff, his Prehensile Hair and his fondness for aerial attacks all call to mind an ape.
- Bifurcated Weapon: His staff can actually become an oversized nunchaku.
- Big Ol' Eyebrows: Gennosuke and Danjou's are nothing compared to this guy.
- Carpet of Virility: Apart from his face, hands and feet, his whole body is covered in a layer of hair so thick and long that Okoi can't get at his skin through it. This foils her efforts to leech his blood, allowing him to kill her by extending his chest hair as dozens of fine needles that pierce straight through her body.
- Carry a Big Stick: His weapon in the novel is described as a club.
- Hoist by His Own Petard: Killed by his own hair under the influence of Hyouma's attack.
- Jerk with a Heart of Gold: He's genuinely affectionate to Oboro, and while everyone shuns her away and think she's useless, he only says she's Just a Kid and hopes she'll grow into her role as leaderess.
Voiced by: Wataru HatanoA skilled warrior and shinobi, he's very protective towards Oboro and possibly in love with her. He obeys the orders of Tenzen, his Evil Mentor, but he's not as evil as him. Can fight with two kama sickles and use his breath to form a deadly Razor Wind attack. Halfway through the series he's blinded by Gennosuke, who sends back his wind at him, but learns how to fight while blind. He's eventually poisoned to death by Kagerou, whom he thought was Akeginu thanks to Saemon mimicking her voice to distract him.
- Crazy Jealous Guy: And he is VERY jealous of Gennosuke. The anime accentuates this.
- Disability Superpower: After being blinded he gains a better sense of hearing, allowing him to fight and kill Hyouma as now he's immune to his gaze.
- Dual Wielding: Sickles. He can even throw them with deadly precision.
- Even Evil Has Standards: He's clearly not okay with the idea of Tenzen forcing himself on a defenseless Oboro. In fact, as this happens, Koshirou is outside the room and clearly forcing himself to not intervene, torn between his loyalty to the one who raised him and his own love for his lady-of-liege.
- Eye Scream: Gennosuke's gaze forces him to damage his own eyes with his Razor Wind.
- Hidden Depths: In the anime, he has a soft spot for kids and is an excellent woodcarver.
- Kiss of Death: Kagerou kills him this way. It says a LOT that this is one of the gentler deaths in the series.
- My Master, Right or Wrong: His loyalty to Tenzen, his Evil Mentor.
- Razor Wind: How his power works: by whistling he can create a vortex that attracts and shreds his enemies to pieces.
- Sinister Scythe: Two of them.
Amayo JingorouA slug man from Iga who can melt his body with salt in order to lay ambushes and move faster. However too much salt reduce him to a pitiful squealing worm. Water can return him to normal. He's deeply afraid of the ocean for obvious reasons. He's killed by Gyoubu who tosses him in the sea, causing him to melt before Akeginu can help him. This makes him the eleventh ninja to die.
- Animal Motifs: Slugs.
- Dirty Coward: Out of all the Iga ninja, he's possibly the least noble and brave.
- Gonk: The novel describe him as looking like "a drowned corpse covered in blue mold". In the anime, he's wrinkly, patchily bold, slightly green skinned, and covered in liver spots.
- Groin Attack: Implied when he tried to rape Okoi without knowing that her skin can suck blood on contact. Painfully.
- I'm Melting: His nightmarish ultimate fate.
- Least Common Skin Tone: Green.
- Orifice Invasion: In his slug form, that's how he kills Jousuke.
- Why Did It Have to Be Snakes?: He's scared shitless of the sea. Justified as, due to the salt in it, his body would melt upon prolonged contact. And that's what happens to him.
Voiced by: Misa WatanabeIga kunoichi, she's a beautiful woman who serves as Oboro's maid and actually cares for her plea. She can expel blood from her skin and use it in battle along with daggers and shortswords. She's in love with Koshirou. She's eventually tricked and captured by Saemon, and stabbed in the heart by Kagerou.
- Bloody Murder: Her powers are a subtler version of this; she can use her blood to create a mist that disorientates her foes, or which can mark them like ink.
- Break the Cutie: She takes her dear Koshirou's death... badly.
- Curb-Stomp Battle: Her fight against Jousuke in the Novel. In the Manga and anime, the fight's against her favor, before Oboro intervenes.
- Knife Nut: Wields a tanto dagger.
- Mundane Utility: In the novel, she uses her blood powers to cover herself with "clothes", so Jousuke wouldn't know he had won a bet between them involving her becoming his wife for the night if he could remove her top.
Voiced by: Miyuki SawashiroKunoichi from the Iga clan and Yashamaru's lover. She can summon and control insects and snakes to do her bidding. She's only sweet and gentle with Yashamaru, and tends to be violent and rude to anyone else. She's maimed and killed in battle by Saemon. This makes her the tenth ninja to die.
- An Arm and a Leg: Saemon takes out both of her hands with a single katana strike before stabbing her on the chest. AAAAARGH!.
- Animal Motifs: Butterflies. Her name means Firefly.
- Berserk Button: Don't even joke about Yashamaru cuckolding her.
- Death Glare: Her default expression around anyone who's not Yashamaru. Though even he gets one when he jokes about Oboro's cuteness. It's really funny.
- Friend to All Living Things: She can use her powers to summon butterflies against her enemies, though she also has a pet snake and in the manga she can control many kinds of bugs. In the novel, is stated that she can use her powers on both insects and reptiles.
- Hand Seals: The only ninja to use them. When she attempts to use them against Saemon, it doesn't go well.
- Hime Cut: Though she does later change her hairstyle to a Tomboyish Ponytail.
- Roaring Rampage of Revenge: Against the Kouga, when she finds out that Yashamaru was murdered.
- Tokugawa Ieyasu: The elderly former Shogun, who appears to be suffering from some sort of throat cancer as evidenced by the bulbous growth beneath his chin. Although retired, he still possesses enough influence within the government to revoke the Hattori truce in order to resolve the succession dispute. Historically, Ieyasu is regarded as an effective but extremely heartless ruler: Basilisk maintains this image of him as he clearly views both Koga and Iga as expendable in the face of ensuring political stability and his family's grip on power, thus forcing them to fight to the death.
- Hattori Hanzou the First (Masanari): The head of a prominent ninja family from Iga Province who would later become chief of the Shogun's intelligence. In the anime, he helped the people of Tsubagakure escape Nobunaga's attack. The peace treaty between Iga Tsubagakure and Kouga Manjidani was originally implemented by him.
- Hattori Hanzou the Fourth (Masahiro): The third son of Hattori Hanzo and the current leader of the Shogun's intelligence. Although he dislikes the idea of turning Koga and Iga loose, his loyalty to Ieyasu compels him to nullify his father's anti-war pact for the sake of avoiding civil war among the other Shogunate retainers. He was among the audience that witnessed the duel between Yashamaru and Shogen at Sunpu Castle and would later witness the duel between Oboro and Gennosuke alongside his adopted son Kyohachiro and Lady Ofuku. Although his demeanor can be considered cold and non-chalant, he was deeply moved by the second duel and enacts a new peace treaty in which the spoils promised to the winner were evenly distributed between both clans. He also recoves the battle scroll from Ieyasu and secures it in a hidden alcove of his Japanese-style Big Fancy House, so that the memory of the 20 chosen ninja would not be completely forgotten.
- Hattori Kyouhachirou: The nephew and adopted son of Hattori Hanzo the 4th (his birth father was Hattori Hanzo the 2nd). Kyohachiro was charged by Hanzo to monitor the duel between Koga and Iga and then report the results to him and Lord Ieyasu. His role is greatly expanded in the anime: in the manga he doesn't appear until the fourth volume (when he reports to his father that Lady Ofuku had departed in an attempt to sway victory in the Iga's favor), whereas the TV series has him appearing somewhat earlier and getting along more or less well with Oboro.
- Nankoubou Tenkai: A Tendai Buddhist monk and political adviser for the Shogunate, he suggested to Ieyasu that since the Tokugawas are a military family, the succession dispute should be settled though some sort of organized duel between ninja instead of valued samurai. As the duel between the Koga and Iga rages on, Ieyasu sends him into the inner castle to keep the peace between Ofuku and Oeyu. He later returns in Basilisk's sequel series, The Yagyu Ninja Scrolls, where he takes on a more saintly role. He is the twin brother of Ashina Dohaku, who serves as the main villain in the second half of The Yagyu Ninja Scrolls.
- Yagyuu Munenori: A Kenjutsu instructor of the Yagyū Shinkage-ryū school, of whom the Tokugawa Shogunate was a loyal patron. He was among the audience that witnessed Yashamaru and Kazamachi's duel at Sunpu and follows the war alongside Ieyasu. Because of their barely reined hostility to each other and the awesome power of their techniques, he views the ninjas of Kouga and Iga as being more akin to demons than humans.
- Ofuku aka Lady Kasuga: The godmother of Takechiyo and leader of the faction supporting his claim to the Shogunate. A cold and heartless woman who murdered her husband's mistress and illegitimate child when they're brought into the household, Ofuku's only redeeming grace is her devotion to her protege Takechiyo whom she considers a surrogate son, at one point even risking her life to save his when the Kunichiyo faction poisoned him., Ofuku attempts to personally intervene despite orders from Ieyasu to the contrary, taking the side of the Iga and forcing Oboro into many problems. After witnessing Oboro's suicide, Ofuku rashly orders her samurai to asassinate Gennosuke, only to witness them die at the hands of his dojutsu. Although Gennosuke decided to spare her life, Ofuku is mentally crushed after the Iga's apparent loss; as punishment for her scheming, Hattori Hanzo decides to keep her in the dark regarding how Gennosuke abdicated victory.
- Princess Oeyo: The consort of Ieyasu's son, the current Shogun Hitetada. Although she gave birth to both Kunichiyo and Takechiyo, she favors Kunichiyo and leads the faction supporting his claim to the Shogunate. Oeyo is just as heartless and manipulative as Ofuku, her rival from long before the succession dispute, and is suggested in the anime that she or one of her followers poisoned poor Takechiyo's tea.
- Takechiyo: Ieyasu's eldest surviving grandson, represented by the Iga. His slow witted nature is the basis of the succession dispute. He will grow into Tokugawa Iemitsu.
- Kunichiyo: Ieyasu's second grandson, represented by the Kouga. Although the younger of the two brothers, Kunichiyo's intelligence and cleverness has caused many within the government to view him as more deserving of the Shogunate over his elder sibling. He will grow into Tokugawa Tadanaga.