Ikoma

Ikoma (生駒, Ikoma) is the main protagonist and a young steam smith who formerly made a living in Aragane Station working with steam engines. He and his friend Takumi developed a steam weapon called "Tsuranuki Zutsu" which Ikoma believes is the best way to fully destroy a Kabane. However, during Kabane's attack on Aragane Station, he got turned into a Kabaneri, boarding the Koutetsujou in hopes of arriving to Kongoukaku to investigate the Kabane.

Appearance
Ikoma is a bespectacled young man of average height and build. He has golden-brown eyes, and messy, brown-green hair. After being bitten by a Kabane, a lock of his hair turned white (presumably from biological stress) and the rest became a lighter green. His glasses are missing a lens on the left frame while the lens on the right frame is tinted green.

Ikoma often wears his steam smith uniform, which is considerably torn after his first encounter with the Kabane. In order to stop the Kabane virus from spreading to his brain, he bolted a series of metal and leather tourniquets/harnesses to his shoulder and torso. He also wears a tight collar around his neck, which helps keep the virus at bay.

At Shitori Station, he wore a light pink robe over his uniform.

Personality
Ikoma is a determined individual set on destroying the Kabane once and for all. This desire stemmed from the loss of his younger sister five years ago, and his haunted sense of survivor's guilt for running away from his sister when she needed him most, and for putting her down with a suicide bag. He wears a stone he and his sister found as a memento of this goal, and looks at it whenever he needs to gather courage.

Ikoma also has a strong sense of justice and righteousness, instinctively prioritizing the lives of others before his own survival. At the start of the series, he was often teased by his steamsmith colleagues for wanting to be a hero. He defended an innocent man from being accused as a Kabane, and was subsequently beaten and thrown into jail. When he survived the infection, he was elated at the fact that he could help others who are bitten as well. As the series progresses it is evident that he is not self-righteous, nor a glory-seeker. He lives up to his "lofty words" of not "losing your humanity to fear". He worries about becoming a Kabane while aboard the Koutetsujou and infecting everybody, and initially kept refusing to be brought onboard by Takumi and Mumei.

While Ikoma is generally level-headed and patient, especially when it comes to dealing with Mumei, he can be hot-headed. One example is when he rebuked the bushi upper class for being cowards and "losing their sanity", something which they scoffed as "lofty words spoken by someone who doesn't fight the Kabane and is protected by the bushi".

Despite some antagonism with the bushi samurai class, Ikoma speaks respectfully when presenting his strategies and equipment, aware that he is of a lower class. He shows more regard for authority than Mumei, and is sometimes shocked by her rebellious attitude.

Ikoma is also a creative and independent thinker, gifted at engineering/tinkering. He prefers to work on his own projects in his workshed/home, sometimes cutting work hours to do so. He developed the Tsuranuki Zutsu (jet bullet steam gun) with help from his best friend Takumi, which is the only known weapon that is able to pierce the caged heart of a Kabane in a single shot because of its superior penetrating capabilities. This gun (and its blueprints) became a key bartering tool for the Aragane station refugees to get food and medicine at other stations. He also developed blades coated with Kabane heart-cage metal for the bushi samurai class, which are also able to pierce Kabane heart cages. Kurusu wields a prototype. Ikoma does not appear to be religious or superstitious, as he believes the Kabane is caused by a viral infection, not a curse.

Ikoma is also quite proficient at Kabane biology, probably because it is part of his job to clean Kabane body parts and blood from Hayajiros that arrive at Aragane station. A little eccentric, he collects Kabane body parts eg) hearts and common carotid arteries to study the course of viral infection, and was first called the "corpse gatherer" by Mumei.

West Gate Breach Arc
At the start of the series Ikoma is seen working on his imperfect jet bullet steam gun at night. In this trial, his gun fails to penetrate a thick slab of steel as hard as the cage around a Kabane's heart, leading him to swear in frustration.

As day breaks, Ikoma heads to work late, presumably because he slept in. He is teased by his steam smith colleagues as a wannabe "hero", suggesting that this happens regularly. After a brief discussion with his best friend and reluctant partner/accomplice in jet bullet steam gun development and Kabane research, Takumi, Ikoma realises that he missed a crucial step in his design. Takumi suggests that he should increase the explosive power, since they increased the cavity of the barrel. At this exciting epiphany, Ikoma is about to run back home and start over again, when the bushi (warrior upper class) princess and heir to Yomogawa family, Ayame Yomogawa, arrives with her escorts and asks for her father's steam gun to be checked. Ikoma is assigned this task by the chief, to his quiet annoyance. A colleague, apparently jealous of Ikoma's opportunity to interact with the "beautiful" Ayame, calls out that it's Ikoma's "chance to be a hero". This piques Ayame's interest, and she asks him if wants to be a hero, to which he replied without meeting her eyes that he just hated running away.

Before Ayame could question Ikoma further, the Koutetsujou (Iron Fortress) drew into the station a day early, to everyone's surprise. Ayame's father, chief of Aragane station, explains that the loss of another station to the Kabane invasion meant a shorter route. This stirred fears that the station will not hold for much longer.

After inspections were complete, the steam smiths set to maintenance work, cleaning and repairing the Koutetsujou. Ikoma shows Takumi a Kabane heart stuck to a wheel, which had an enlarged common carotid artery, suggesting that the virus passes through this artery to get to the head. Then, despite Takumi's protests that it was against the rules, he quickly tucks it into this bag, explaining that it was "rare to get such a good specimen". As they are speaking, Mumei, dressed in an expensive short kimono and holding a child's toy, jumps down from an adjacent carriage, apparently having bypassed the inspections. The sight of Mumei provokes a reaction in Ikoma for an unknown reason. Takumi notes that she is probably the child of someone of grand status. When accosted by a guard insisting that even children have to be inspected, she flicks the toy rubber ball at the guard's nose, showing incredible dexterity, while quoting her "ani-sama" (older brother) that one "shouldn't judge a book by its cover". The Yomogawa chief stops the guard from retaliating, saluting and showing respect to Mumei and her companion, Shimon. As special guests, they are exempt from inspections and are to be taken straight to the Yomogawa mansion, to the surprise of all present.

At that moment, there is a shout accusing someone of being bitten by a Kabane. Half-naked, a man runs out from the train in terror, exclaiming that he's not a Kabane. The bushi, in a show of power, surround him and are about to kill him. Ikoma intervenes, shouting that the bushi's own rules are to watch a suspected man for three days, not kill him out of cowardice. This attracts Mumei's attention and interest. For his provocative words and disrespect, Ikoma is beaten by the bushi. In the beating, the stolen kabane hearts spill out of his bag, garnering disgust, fear and suspicion from the crowd. The accused man attempts to run away in the chaos and is shot. Ikoma is reprimanded by Chief Yomogawa for his "lofty words", afforded only by one protected by the bushi and does not face the Kabaneri. When Ikoma insists that he too will fight, Kurusu smashes his windpipe with the blunt end of a gun, and he is thrown into jail under suspicion that he is a Kabane (one reason being the corpse gathering). Ayame protests her father's actions, but her father silences her, saying that it is a bushi's duty to protect order.

Later that night, Mumei feigns sleepiness to get out of the talks with Chief Yomogawa, and secretly visits Ikoma at the jail. He had been trying to pick the lock without the guard noticing. After a brief introduction, Mumei, curious, asked him if he knew that the man wasn't a Kabane. Ikoma said he didn't; he just didn't like that the bushi were being cowards and killing innocent people. Mumei laughed and said that Ikoma was interesting, because normal people are "generally cowards, and they can't do anything about it". Ikoma disagreed, saying that it was unthinkable to him that people have no choice but to kill others out of fear. They cannot lose their humanity to fear. This makes Mumei smile.

While Mumei and Ikoma had been talking, the Kabane secretly arrive on board the Fusoujou, exactly on schedule. The train had been completely taken over. Kabane steam smiths sounded the horn, falsely signifying that all is well. When the train does not slow down, the station workers notice that something is amiss, but it is too late. The train derails and crashes into the west gate, flinging a few carriages into the station. People begin to flee as the bells ring in warning. Mumei, suddenly serious, leaves Ikoma. Ikoma takes advantage of the chaos to pick the lock with one hand and escapes. He baits a Kabane with his blood, leaving a trail to his workshed. The Kabane crashes in through the roof, showing some tactical ability. After a tense struggle, Ikoma manages to kill a Kabane with the modified jet bullet steam gun prototype. However, his elation is short-lived as he discovers a bite wound on his right arm.

Meanwhile, Mumei and Shimon, almost immediately recognising that the station was lost, run towards the Koutetsujou. Chief Yomogawa gives Ayame instructions to come to the Koutestujou upon his signal that it is secure. After some fighting with the Kabane along the way, Shimon apologises to Mumei that she must carry on alone, as he had been bitten. It is also revealed that Shimon is merely Mumei's escort; he is of lower rank than her. She nods gravely, and blesses him with "May karma smile upon you" as he uses a suicide bag. It is later shown in the series that this quote is taken from her beloved "ani-sama", Biba.

Ikoma quickly tests his hypothesis that the virus can be stopped if the infection does not reaching the brain during the infectious phase. He cauterises his wound with a brand in an attempt to kill the virus, and bolts metal and leather tourniquets to his flesh, restricting the blood flow to his brain. When this fails, he strangles himself using a neck collar strung to the ceiling with a belt, in a last-ditch attempt to not turn into a Kabane. He remembers his sister, and this determination to never run away again gives him the courage to finish the process. The infectious phase over, the virus recedes suddenly and Ikoma releases himself, gasping for air. A part of his hair turns white due to the stress. Ikoma then celebrates the success of the gun and the rudimentary "treatment", a step closer to curing those infected.

Mumei runs on alone and encounters a stray Kabane. After removing the ribbon around her neck, much like Ikoma's collar restraint, she decapacitates the Kabane in one sideways kick. She struggles to remove her clogs from the indent left by the superhuman blow, so she leaves her shoe. Running, she calculates to herself that the refugees might only be able to make the ~8 miles to the Koutetsujou if they leave now.

Ayame struggles to hold back the bushi, who insist that they should set out immediately despite not receiving the promised signal from her father. The bushi, frustrated at her lack of experience (and calculation), say that they must leave now, or they will never make it. Before the argument can get out of hand, Mumei arrives in her battle gear, and takes charge quickly. She puts down dissension by force, finds someone to drive the Koutetsujou, and instructs them to follow the path she'll clear for them. She then kills all the Kabane in 110 seconds, astounding everyone. They make it safely to the Koutetsujou, but fearful inspections hold up the evacuation process.

Takumi arrives at Ikoma's workshop in a straw hat, armed with nothing but a pitch fork, worried enough to overcome his fear and find Ikoma. Ikoma explains that their weapon was a success. After some funny dialogue, Ikoma reassures Takumi that though he was bitten by a Kabane, he didn't transform to one. Ikoma and Takumi then travel to the Koutetsujou, Ikoma too absorbed about the implications of their jet bullet gun to disguise his bite wounds. Takumi puts a red "hero" cape on him, slightly concerned.

When the two arrive at the Koutetsujou, they are stopped by guards and asked to remove their clothes for inspection. While Ikoma is ready to do so, Takumi stops him, concerned that the guards will not believe his story in their panicked state. Two Kabanes appear, sending everyone running to the train - everyone except for Ikoma, who is convinced that killing them with his jet bullet gun will make the guards accept him on board. However, Mumei appears and kills them in a flash, surprising Ikoma and Takumi. Ikoma recognises her and calls out to her just as she walks past him to the Koutetsujou, tired. Mumei does a double-take, asking Ikoma if he "changed his look". Ikoma evades the question, saying that she looks different too. Ikoma praises her as strong, but she downplays it modestly as "just a little", distractedly trying to identify something different about Ikoma. Still in awe, Ikoma asked if she led everyone to the train. Mumei nonchalantly replied that no, they simply followed her, despite the fact that what Ikoma guessed was true. As she finishes tying a ribbon around her neck, Mumei leans in and sniffs Ikoma's torso, realising that he has become a Kabaneri. She tells him that he is indeed not normal, and offers him a ride on the train. When Kurusu stops him and suspects him of being a Kabane, Mumei interjects and says that he is not a Kabane. Ikoma and Takumi then get on the last carriage, close to the boiler (where Ikoma can connect his jet bullet steam gun).

Another horde of Kabanes attacks Koutetsujou. Ikoma saved some civilians from a steam pipe, he stopped the pipe with one hand and was able to withstand the heat. A Kabane was able to penetrate the metal door, Ikoma fighted off the Kabane with his new weapon. He killed the Kabanes then to realize he exposed the inner of his robe; exposing his  heart as a  Kabane's. Kurusu shot him and he was thrown out.

Later, a problem appeared. The switch bar for the bridge was not working so they needed to use the manual bar to lower the bridge. The only problem was it was outside and swarming with Kabanes. Ikoma fights off the Kabanes, bitten a lot of times but he didn't mind the pain. He lowered the manual bar and the Koutetsujou was able to move on.

He cried due to frustration, while Takumi threw out a hook in order to rescue him. Mumei went to Ikoma's side and hooked Ikoma's feet. He was dragged by Takumi. He was soon given a suicide bag by Kurusu. Mumei explained that he was not a Kabane nor a Human. Instead, he had become a Kabaneri.

Journey to Kongoukaku Arc
Ikoma attempted to leave the train, stating that he could incidentally turn everyone into Kabane, as Mumei kicked him and says that he has a mind of human, while his body is that of a Kabane. While Mumei revealed her goals of arriving to Kongoukaku, Ikoma tried to interrupt, only to be beaten by Mumei once more. After having a nightmare, Ikoma suddenly woke up to Mumei in the boiler car, who explains why she needs to go to Kongoukaku, while requesting the former to be her guardian. Ikoma protested, while Mumei mockingly kicked him across the room. He followed her to the other room, as Mumei claims that she smelled a Kabane.

While speaking with Mumei, Ikoma explained his past and his sister's death, blaming himself for not being able to save her. They are then attacked by a group of people, who are stopped by Ayame. While Mumei calmly leaves, Ikoma is left with Ayame, who attacked him with her knife, questioning his motives. Ikoma said that he has made a vow not to run away, as his purpose in life is to destroy the Kabane. Ayame backs off, asking if the group still doubts his true affiliation. After having a brief conversation with Ayame, Ikoma succumbed to his wounds due to the blood loss and hunger, pouncing her on the floor, mindlessly attempting to bite her. However, Kurusu comes in and angrily berates him about his actions, pointing his gun at him. The conflict is soon stopped by Mumei, who says that the wave of Kabane is closing in.

As the locomotive itself is overtaken by a certain number of passengers, other steam smiths are also thrown in a room where Ikoma and Mumei resided, as civilians accused them of sympathizing with Kabane, planning to detach their car from the rest of the fortress. However, a large group of Kabane led by Wazatori attacked the locomotive, slaughtering the passengers nearby. Ikoma recalls his sister's death while watching the Wazatori murder a woman. Ikoma suggested he and Mumei exit the service hatch and chase after the Kabane.

The group went on the top of the locomotive, discussing on how they will eliminate the threat. As Mumei informed the steam smiths about the name of the cave, they concluded the time of their ambush. As Takumi gives Ikuma his gun, they fight through the small horde of Kabane infesting the top, while nearing the main threat. Mumei gradually got exhausted, prompting Ikoma to face the Wazatori alone, placing her trust in him. Ikoma is weakened due to his need of blood, pleading someone to help him in order to kill the rampaging Kabane. Ayame came out of the car, forming a contract with Ikoma by offering her blood in exchange for his protection. Ikoma ambushed the Wazatori from above, pointing his gun into the Kabane's heart, ultimately killing it. The group celebrated their win.

Ayame declared that Ikoma and Mumei will travel with the group.

While on travel, engineers developed a new gun (with the help and assistance of Ikoma) based on Ikoma's piercing gun. Ikoma also made an enhanced experimental version of katana that has its durability increased (currently untested). After the Koutetsujou is blocked by a crumbled metal construction, Ikoma formed a plan with the rest of the personel on how to unblock the passage for the locomotive. However, Mumei disagreed with Ikoma's plan to use the longer way to the crane in order to avoid the Kabane.

Later on, Ikoma visited Mumei and questioned why she doesn't want to aid them. After a short argue, Ikoma warned her not to attack the Kabane nest directly. As they arrived near the crane, Ikoma noticed Mumei rushing towards the center of the nest, and chased after her. In the crane, Ikoma angrily looked at Mumei for not following the plan, and activated the machine. After a large herd started engulfing the construction, the Bushi warned Ikoma about retreating to the locomotive. Ikoma goes after Takumi and takes control over the crane himself, in order to protect the two. He noticed exhausted Mumei going towards the Kabane to fight them alone, and rushed to her after she got overpowered and kicked off the crane by a Wazatori, stopping the crane in the process.

As he carried her to the passage underground, they get crushed by crumbling rocks from the damage done to the construction.

They survive the accident, with Ikoma being able to move, and Mumei being trapped under rocks. Ikoma tried to free Mumei, although unsuccesfully. A large group of Kabane attacked the two, and Ikoma went to fight the herd in order to protect Mumei. After the rescue arrived, Ikoma and Mumei are recovered and are soon reunited with everyone at the train.

Ikoma is once again tasked to control the train crane in order to move the damaged tower, which was initially the plan, and does so succesfully now. However, the Koutetsujou is targeted by a Fused Colony, and after a failed shot, Ikoma and Kurusu went out to face the Kabane approaching the vehicle. When the Fused Colony is defeated, Ikoma saved Mumei from a fall and retrieved her back to the car.

Powers and Abilities
As a proficient engineer and inventor, Ikoma is intelligent, resourceful and thinks well on his feet. He designed the Tsuranuki Zutsu, the only weapon known to be able to pierce a Kabane's heart cage in a single shot, and Kabane metal coated blades for the bushi samurai. He thought quickly enough to stop the Kabane virus from spreading with scrap parts around his smithy. He also exhibited considerable skill as a lock pick as he managed to unlock his cell while Aragane station is overrun, with just one hand. When under pressure, Ikoma is shown to have high pain tolerance, as he withstands bolting his metal restraints to himself, slicing his wrists, and cauterizing his bite wound with a burning piece of wood.

As a Kabaneri, Ikoma gains many abilities:

Increased Strength and Heat Resistance: Compared to a human, Ikoma's strength and heat resistance is greatly increased. He is able to hold and bend a scalding hot pipe with his bare hands with no indication of pain, as well as return it to its proper place with a light tap. With training from Mumei, he is also able to easily defeat Wazatori, a much more powerful variation of Kabane.

Enhanced Durability: Ikoma's body is considerably stronger and more resistant, as he was able to take a bullet to the chest and still fight multiple Kabane.

Enhanced Regeneration: His wounds evidently regenerate much more quickly, his vitality making him capable of recovering from a wound that is mortal to humans, like when his stomach is bitten through.

Immunity: After his conversion into a Kabaneri, Ikoma is immune to Kabane bites, as he has been bitten several times throughout the course of the series without any implications.

Kabane restriction/inhibitor: Similar to Mumei, he wears a restraint around his neck in the form of a metal harness. It is possible that Ikoma could potentially be more powerful without his restraint as well. However, as a half-Kabane, he requires blood to function fully and will begin to drift towards being a Kabane without drinking any.

Enhanced learning speed: Mumei claims that Kabaneri are very good at copying others' actions, and can reproduce complex movements after having seen it only once. Ikoma uses this ability to learn hand-to-hand combat from Mumei and swordsmanship from Kurusu.

It appears that Ikoma is potentially more powerful than Mumei, since he is able to perform similar feats without removing his restraint. This could be because he takes more care of his body eg) eating "lunches" even though he's not hungry.

Takumi
Takumi is Ikoma's loyal friend. They are often seen together, and as fellow Steam Smiths, they developed a gun that is able to pierce Kabane's heart. Ikoma puts great trust in Takumi, uncovering his bite wound to him. Takumi cares a lot about Ikoma's idealistic goals, and is usually the more sensible one of the two.

Mumei
Mumei is a Kabaneri, and like Ikoma she lost all of her biological family to the Kabane. The two became close due to their shared histories, and although they argue, it is clear they do care for each other. This is demonstrated when Ikoma abandons his mission to save Mumei's life, despite the fact that she deliberately spited his battle strategy, and expresses concern for her well-being when she appears to be sad or aloof. Likewise, Mumei seems to be comfortable around Ikoma, telling him a little of her past and not being afraid to talk to him about her fears.

When Ikoma learned about Mumei's original name, Hozumi (which means sea of rice), he made his mind to turn Mumei back into a human, kill all the Kabane and take back all the stations and rice paddies - so that he can "fill her belly with rice", just like how Mumei's mother wanted to. Ikoma is protective of Mumei, holding her adopted brother Biba responsible for erasing the name she was born with, calling her "nameless" and teaching her that weak are to die. It is yet to be determined if the two are developing romantic feelings for each other, or are just developing a brother/sister bond. In feudal Japan, girls were of marrying age as soon as they started menstruating after all.

Trivia
生駒
 * Ikoma is the first person in the series to be seen turning into a Kabaneri.