is a Japanese light novel series written by Chūgaku Akamatsu and illustrated by Kobuichi. As of June 2026, 45 main volumes have been published by Media Factory under their MF Bunko J label. A manga adaptation by Yoshino Koyoka started serialization in the seinen manga magazine Monthly Comic Alive in September 2009. An anime adaptation aired between April and June 2011. An original video animation (OVA) episode was released on December 21, 2011. A spin-off manga titled Aria the Scarlet Ammo AA by Shogako Tachibana was serialized in Square Enix's Young Gangan magazine from November 2010 to May 2018, with an anime adaptation by Doga Kobo airing between October and December 2015. A new short anime has been announced.
Plot The setting of the story features , short for , a national qualification established to counter worsening crime conditions around the world. The Butei holders are trained in various specialized fields, and are permitted to possess various weapons and capture criminals. Kinji Tōyama is a student at Tokyo Butei High, a universal educational facility for the training of Butei. At this school, students with an aptitude for the work undertake special training in order to learn the path of the Butei. Shortly after Kinji decides to quit the Academy for personal reasons, he is attacked by the Butei Killer, a criminal notorious for eliminating Butei—a case of the hunters becoming the hunted. The elite Butei Assault prodigy Aria H. Kanzaki comes to his rescue and from that moment on, Kinji's future as a Butei changes drastically.
The side story, Aria the Scarlet Ammo AA, follows Akari Mamiya, an E-ranked Butei who applies to become Aria's "Amica".
Characters Main characters
A student at Butei High School. He was initially ranked E (lowest combat rank) due to missing the third term's final examination. However, when he is sexually aroused (such as sticking his face in a girl's chest, getting kissed or by him kissing a girl) he enters a state known as "Hysteria Mode" in which his cognitive and physical abilities increase to around thirty times his normal state, which allows him to perform feats of near-superhuman strength and skill, such as accurately shooting up the muzzle of an enemy gun, swinging his knife at supersonic speeds, and accurately shooting enemy bullets out of the air. Hysteria Mode is a genetic trait that all members of the Tōyama family possess, and is stated to be a highly evolved version of the natural male instinct to protect women. As such, when in Hysteria Mode, Kinji's major weakness is the fact that he cannot directly harm women, though he is still able to fight and restrain them without directly hurting them. In addition to this, Hysteria Mode also causes Kinji to develop a suave and seductive attitude towards women, which makes him very attractive to them while in Hysteria Mode. He is currently enrolled in the Inquesta department, though in the past, he was a prodigy (being rank S) of the Assault department, the most dangerous department in Butei High. Over the course of the series, Kinji grows to respect (and eventually develops romantic feelings for) Aria. He proves his feelings for Aria by kissing her on the lips in episode 5, though this is done to calm her down. Currently, his feelings for Aria are so strong that even the slightest bit of sexual/romantic involvement with Aria will instantly activate Hysteria Mode. His gun of choice is a Beretta 92F (which has been illegally modified to fire a three-round burst; he refers to it as the Beretta Kinji Model). He also wields a butterfly knife. In Volume 6 of the light novel he obtains a black Desert Eagle (which has been modified to fire in bursts as well as auto) which belonged to his father and a double-edged seax (modified with a hidden sheath and a reinforced rubber handle) which belonged to Sherlock Holmes. When he activates Hysteria Mode, he is able to dual-wield both the Beretta and Desert Eagle as well as the Butterfly Knife and the Seax, making him earn the title of "Quadra of Mimicry" in the series.
A transfer student to the Butei High School in Japan. An "Assault" department elite rank S (the highest rank), she wishes to recruit Kinji into her team after their encounter. She has earned the title of "Quadra", meaning someone who can dual-wield both guns and swords. Her weapons of choice are two Colt Government Model M1911A1 semi-automatic pistols (one black and one silver) with custom hinge type triggers (as opposed to the traditional straight pull triggers of the M1911) and custom grips. She also uses two undersized Japanese swords known as kodachi. The "H" in her middle name stands for "Holmes" as she is a descendant of Sherlock Holmes himself, and her full name is Aria "Holmes" Kanzaki IV. She is very short for her age. Her stunted growth is due to a bullet embedded in her back made of a special material known as HihiIrokane. Irokane is a special element that can grant a normal human superpowers. HihiIrokane is red Irokane and in order to make use of its properties requires a childish nature and prideful personality. Although Kinji has learned about the special properties of the bullet and the potential powers it gives her, Aria seems largely unaware of anything unusual about the bullet or herself. All she knows is that a stranger shot her for unknown reasons and that the bullet can't be removed safely. As a side effect of the HihiIrokane bullet lodged within her, Aria's eye and hair color (which were originally sapphire blue and flaxen blonde) changed to a deep ruby and pinkish strawberry blonde respectively. Her mother is Japanese and her father is half English, half Japanese. Her paternal grandmother is a member of the British royal family, having been knighted and received the title of "dame". Aria develops feelings for Kinji after they kiss in episode 5, and gets jealous when other girls approach him.
A female student attending Butei High School and Kinji's childhood friend. She is enrolled in the special department known as SSR and her Butei rank is A. She's the current student council chairman, and president of various clubs including the gardening club, handicraft club, and girls' volleyball club. According to Kinji, she is a perfect Japanese beauty except for one flaw - jealousy, which turns her into a berserker who assaults any girl approaching Kinji. When she finds out that Aria is living with Kinji she tries to murder her. She is shown to love Kinji to the point that she will do anything for him. Kinji and Shirayuki kiss in episode 8, and since then Shirayuki's feelings for Kinji have increased to the point that she is willing to appear nude in front of him in order for him to notice her. She uses a Japanese sword named Irokane Ayame as her weapon of choice. It is later revealed that her name, Shirayuki, was an alias used to conceal her real name, Himiko.
A female student at Butei High School and a friend of Kinji's. She is enrolled in the Inquesta department along with Kinji. Although often considered the biggest idiot in Kinji's class, this is a deliberate burikko facade which she drops when she is forced into dangerous circumstances. She has a talent for intelligence assessment and, at Butei High, gossip. She enjoys customizing her uniform in an Elegant Gothic Lolita style. She wields two Walther P99s and two knives and, much like Aria, has earned the title of "Quadra". Near the end of the first volume, Riko reveals that she is a descendant of Arsène Lupin. Her real name is Riko Mine Lupin IV. Riko also reveals that she is the Butei Killer. She appears to have an inferiority complex towards the first Lupin and wants to exceed his legacy. The reason for this, and why she despises being referred to by her generation's number, is due to the circumstances under which she grew up. Orphaned at a young age, she was taken in by Vlad/Toru but kept locked in a cell with very little food and muddy water, and eventually was used as an experimental subject by Vlad/Toru. During this time he repeatedly told her that she's worthless (since she hadn't inherited any of the past Lupins' abilities) and that her only redeeming quality was that she could be used to produce another generation of the Lupin name, Lupin the V. Riko was eventually released from her captivity by Vlad/Toru and promised complete freedom provided that she was able to surpass the original Lupin. Her original plan was to recreate the historical encounter between the original Holmes and Lupin, with Aria and Kinji playing the roles of Sherlock and Watson. By defeating both of them she would surpass her ancestor since the original encounter ended in a draw. This plan fails, but Riko's able to convince them to aid her in recovering a memento from Vlad/Toru. After helping Kinji and Aria defeat Vlad, Riko helps Aria by providing evidence that Vlad/Toru, and not her mother, Kanae Kanzaki, was truly behind all of the Butei Killer murders, and so reducing Kanae's sentence and delaying her impending execution. Riko appears to have feelings for Kinji, but these feelings may not be completely healthy because she constantly attempts to seduce Kinji - attempts which fail since Kinji is able to see through her machinations. She kisses Kinji after he points out that by defeating Vlad/Toru, she has surpassed her ancestor and can finally take pride in herself, perhaps sparking a more healthy interest in him. Riko and Aria have several characteristics in common: they are short, both have earned Quadra status, both wear their hair in twin-tails, both are the third generation scions of famous ancestors, and lastly, both are romantically interested in Kinji. Her surnames are derived from Lupin III and Fujiko Mine, and she is purportedly their child; for copyright reasons, the identities of her parents are unknown.
The Snipe department's ace, Butei rank S. She has no family name and is habitually taciturn, impassive and indifferent to fashion. Kinji later finds out that this, along with her hair color, is due to the influence of large quantities of RiriIrokane in her birthplace. RiriIrokane is Azure Irokane and it bestows the ability to nullify other powers when the subject is calm. However, according to a Hotogi Historical Record it 'hates' human hearts and the princesses of the Ulus (to whom Reki belongs) revere RiriIrokane and offer their 'hearts' to it. She's always seen wearing Sennheiser PMX990 headphones through which she apparently listens to the sound of wind from her homeland (somewhere between Northern Mongolia and Siberia). Her signature quotation is "I am a single bullet. It has no heart. Therefore, it does not think. It just flies straight towards its target", which she always say before she takes a shot. Her sniper skills are so high that she can shoot anything within a 2 km radius without missing her target. Her personal weapon is a SVD (Dragunov Sniper-Rifle) with an attachable bayonet. In the middle of volume 3, Reki tames a wolf in a matter of 5 minutes, which she later names Haimaki, and trains to be a Butei dog. From then on, she lives together with Haimaki in her room in a girls' dormitory. Kinji has visited her room at least twice up to volume 6 of light novel and has noted how bare and simple it is. Reki also sleeps upright with the Dragunov in her hands, perhaps to prevent an ambush attack according to Kinji. On noting that Reki doesn't possess any clothing other than a number of school uniforms, and as a part of his Lima syndrome plan, Kinji buys her a casual outfit as a present. Reki cleans up nicely; in fact, Kinji was left speechless after witnessing her dressed-up appearance in volume 6.