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, light green hair. After being first bitten by a Kabane, his hair partially turns white and his skin takes on a pale green tint. 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 bolts and brands a shoddy harness to his body, which encompasses his right shoulder and some of his right torso. He also wears a tight collar around his neck, which helps keep the virus at bay.

Personality
Ikoma is determined and foolhardy individual, his eyes set on making a difference in humanity's fight against the Kabane. His outstanding willpower to fight the Kabane and do the right thing often puts him in tough situations, but is also his best survival mechanism.

His greatest desire is to destroy the Kabane once and for all, which began after he witnessed the death of his beloved sister at their hands five years ago. However, he also maintains a keen sense of justice, prioritizing the lives of others before his own survival. After he survives being infected, he is elated at the fact that he could help others who are bitten as well.

Ikoma is a proud character who maintains his honor in spite of adversity, which clashes with his inherent desire to help others. It is because of this that he lives on to protect others aboard the Koutetsujou, despite the danger his existence poses for everybody.

Ikoma is also a tinkerer, born from his work with steam engines. He develops the Tsuranuki Zutsu with help from Takumi, which is the only known weapon that is able to pierce the caged heart of a Kabane in a single shot.

West Gate Breach Arc
Ikoma works on his imperfect steam gun, at that trial his gun failed to penetrate a bar of metal which is almost as hard as a Kabane's heart.

He went to his job as a steam smith and met his friend and partner in developing the steam gun and researching Kabane, Takumi. Soon, Ikoma told Takumi how the trial was and Takumi suggested to add the explosive power. Princess Ayame Yomogawa arrived and asked her father's steam gun to be fixed. The chief called Ikoma, and he was called as "hero" by his workmates. The princess asked if he wanted to be a hero, he replied he just hated running away. The Koutetsujou arrived the station early because of the Kabane invaded another station. Ikoma did his work cleaning and repairing the Koutetsujou and collected Kabane's carotid artery and explained that it was bigger. He first saw Mumei here. A person was accused of being bitten by a Kabane and Ikoma exclaimed that the man was not to be killed but he was to be under supervision. Ikoma was beaten by the Bushi and the man was killed and Ikoma was thrown to jail.

Mumei visited Ikoma and asked him if he knew if the man was a Kabane. Ikoma explained that humanity cannot escape fear.

The Fusoujou arrives carrying nothing but Kabane, it crashed and entered the station with Kabane. As the Kabane manifested the station, Ikoma escaped from the jail and went on to finish his steam gun. He used his blood as bait. He managed to kill a Kabane but he was bitten and the virus started to infect his body. Ikoma strangled himself using a belt and a machine to stop the virus from reaching his brain. A part of his hair was changed from light green to white after the process to stop the virus.

Takumi, arrived in Ikoma's workshop and Ikoma explained that his weapon was a success but he was bitten by a Kabane and he didn't transform to one. They traveled to meet up in Koutetsujou. They were stopped by guards. Kabanes appeared and Mumei killed the Kabane near the Koutetsujou. Mumei asked Ikoma if he had changed his look and smelled him and told him that he was not normal. He was stopped by Kurusu and Mumei told them that he was not a Kabane.

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 ship, 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, offering her blood with the others.

Powers and Abilities
As a human, Ikoma is rather intelligent and thinks well on his feet. He is a proficient engineer, able to design the Tsuranuki Zutsu, and thinks quickly enough to stop the Kabane virus from spreading with scrap parts around his smithy. He also exhibits some 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.

Enhanced Strength: As a Kabaneri, Ikoma's strength 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 effortessly. He is also able to easily defeat Wazatori, a much more powerful variation of Kanabe.

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.

Similarly 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.

Takumi
Takumi is Ikoma's close friend. They are often seen toghether, 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.

Trivia

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