Takeo (Kor. 타키오) is a Modified Human and the series's stock character. He is an ex-member of the DA-5, which was a special forces team of the Union. Unlike the others, he was tricked into working for the Union by Dr. Aris, who pretended to be his sister Teira being held captive by the Union. He eventually finds out the truth and switches sides along with Tao, joining Rai and Frankenstein. He currently works as a security official at Ye Ran High School. He is a member of the RK-5 and his codename is 'No. 2'.
Takeo cares deeply about humans, which can be observed in the fact that he treats younger kids with a high amount of compassion because of his memories with his "sister". He demonstrates his kinder nature by giving M-21 water when the former experiment is imprisoned and tortured by the members of DA-5. He also enjoys mingling with citizens around the area in which his team currently operates in, though he is quickly chastised by his teammates for doing so. Takeo seems to be a good-natured person and only does what is necessary in order to keep his sister safe from the Union. After he is disillusioned from Dr. Aris' lie and comes to join Frankenstein's household, he freely shows his softer, albeit more regretful, nature with his newly found comrades.
He is also shown to have a more down to earth personality than his friend Tao as he tells him to stop talking (albeit unsuccessfully) when he informs Frankenstein about him being impersonated, closing the school and giving everyone in the facility paid leave.
Takeo was once a member of the DA-5 created by Dr. Aris. Believing that his sister was held captive by the Union, he participated in its experiments and followed orders in order to protect her. In Chapter 151, however, it is revealed that this is a ruse concocted by Dr. Aris, who created the facade for the sake of her own entertainment. Takeo is later invited to live in Frankenstein's house after betraying the Union and erasing all traces of his and Tao's existence, which resulted in the Union's belief of their failure and death as experiments.
Takeo debuts in a DA-5 mission on a mountainous region, sniping a target to complete their mission. They are then sent to Korea to investigate Dr. Crombel's work there.
In Korea, as the DA-5 decide to find M-21: the only remaining person from whom they could know about Crombel's experiments, Takeo wanders in the peaceful city by himself. He is robbed by some local delinquents. Shinwoo and Yuna, being on the vicinity, notice it and Shinwoo confronts the bullies. He quickly defeats them and returns Takeo's wallet and apologizes to him on behalf of Korean citizens. Takeo mistakes them for a couple on date. He complements Shinwoo and Yuna with his limited Korean vocabulary; his colloquialism further shocking them. Takeo goes to a cafe with Shinwoo and Yuna where they all have a nice chat and he tells them about his sister. When the children leave, Takeo sits down and notices Shark who has seen him hanging out with the children.
Within a few days, M-21 is caught by Shark and Hammer. Rather following his groupies, Takeo treats M-21 nicely and even gives him water to drink when the others left.
Takeo confronts Frankenstein who comes to check on M-21 from distant. They engage in a fight but Frankenstein leaves when he thinks that the battle is dragging too long. Later, Takeo informs Tao about this encounter.
Elsewhere, Shark finds out that the kid who met with Tao and the children who met with Takeo are friends and Regis is acquainted with them as well. Shark and Hammer capture Regis and the children and bring them to their base. Takeo is shocked to see the kids captured and learns that Shark had been killing everyone he has ever talked to outside of DA-5. Krantz authorizes Shark to kill them all as they're witnesses. Takeo is then positioned outside their base as watchguard.
Outside the base, Takeo grieves over the innocent people that died and the children that were about to die because of him when Frankenstein arrives, this time, accompanied by Rai. Takeo points a gun towards Rai who proceeds to find Regis and the children but Frankenstein steps in the way, enraged at Takeo for daring to point his gun at his master. They have another showdown and Takeo ends up impaled by Frankenstein's projectiles despite using his D.
Takeo makes a last request to Frankestein as the latter advances to kill him. He asks Frankenstein to save the children who are being held hostage inside the building. He states that the children are innocent and that they had gotten involved because of him. He regrets that he would not even be able to apologize. Frankenstein silently leaves him there.
Later Tao is told to get Takeo from there and he is brought along in the house for treatment. Takeo awakens and finds himself in the new place. Tao explains what had happened and how they were intended for Krantz to absorb. Takeo however worries about his sister, Teira who is held hostage by the Union. Tao assures he will look up the matter. But Takeo suggests leaving the place in order to prevent their rescuers from getting involved in further trouble. M-21 intervenes and asks Frankenstein to let them stay to which the latter easily agrees.
Dr. Aris Arc
Takeo accompanies Rai and M-21 to find Frankenstein who has been apparently kidnapped by Dr. Aris and Yuri, the ones who have come to investigate the annihilation of DA-5. Tao directs them to the spot of a blast (coming from the battle between Frankenstein and Dr. Aris’ guards) that gives away the location of Frankenstein.
Upon reaching the place, Takeo finds Frankenstein attacking his sister Teira! He lunges ahead to defend her while Rai and M-21 watch from afar. Frankenstein reveals that the one Takeo is mistaking for his sister is actually Dr. Aris herself. Takeo stands in disbelief and in the fraction of confusion, Aris makes Takeo hostage. She then reveals the truth herself; how she had created the character of Takeo’s sister and played it for her own amusement. Takeo then realizes that the ‘Union keeping his sister hostage’ thing was entirely a fabrication of Dr. Aris. Meanwhile, his life force is getting absorbed by her. Suddenly Aris notices D (the ones Frankenstein has made) in Takeo’s pocket. To everyone’s surprise, Dr. Aris’ desperate consumption of those pills momentarily enhances her and then drops her unconscious. After Yuri flees with her body, everyone returns back home.
After everything is cleared up, Tao and Takeo join Ye-Ran as M-21's colleagues and form the Ye Ran Special Security.
Takeo carries on his duty as part of the Ye Ran Special Security and is also assigned the post of dish cleaner alongside M-21 in the household. One day, a new visitor appears at the school grounds and is surprised at the presence of modified humans in the school that Seira and Regis attend. He is later revealed to be Gejutel, grandfather and clan leader to Regis. Although he misjudges the trio to be power hungry humans who forsook their humanity, Regis attests for their characters. Gejutel stays with the household for a while, conversing with Rai and Frankenstein who he has met after a long time and then departs.
Later, another visitor suddenly arrives at the school and makes his hostile presence known by releasing his aura. The security trio goes to check out the situation and find the troublemaker is another noble, Rael. The trio is object to insults continuously hurled by Rael who finds the presence of ‘man-made toys’ absolutely detestable. A fight breaks out but it is cut short due to Seira’s intervention.
Takeo joins Tao and M-21 in secretly boarding Frankenstein’s private jetplane which is bound for Lukedonia. However, Rai, Frankenstein and Regis disembark just after reaching the Lukedonian skies, unknown to the trio and the plane crashes with the trio inside it. The crash lands them in the Mergas’ territory.
When the trio gains conscious, they find themselves in a treatment facility of nobles. Two Central order guards arrive but the trio is able to withstand their mind control and manage to get out of there. They arrive at the Forbidden Region just in time to help out Regis in keeping the guards away from the mansion. After they reveal themselves to Rai and Frankenstein, the latter is astonished to see them there as it is the least hospitable place for modified humans but Rai allows them to stay at his mansion.
After witnessing Frankenstein's battle with Rajak, the trio follows as Frankenstein rushes towards the castle sensing Rai's release of power. They arrive after the clash of the noble hierarchy has come to a cease and all misunderstandings have been cleared. Rai and Frankenstein have left by then and the arrival of modified humans draws the attention of the nobles. Gejutel quickly introduces them as people Rai has taken under his wings. Later the trio, along with Regis, is escorted to the mansion by Seira. The trio stays at Rai's mansion for the next few days and returns back to their home, the human world to resume their normal lives.
Two newcomers pay a sudden visit to Ye Ran School and one of them engage in a discord with M-21. Takeo along with Tao restrains their friend. Later, those two people join the school as teachers under the aegis of the government. They are actually KSA agents. Within the next few days, the trio catches the agents at using thugs on the children (testing out recruit candidates) which results in Frankenstein taking the opportunity to have the agents dismissed for the sake of student safety.
M-21 vs Na Yonsu
Takeo faces Sangeen when M-21 fights Yonsu at night in the school precincts. They fight until both M-21 and Yonsu realize that none of them are from the Union and can be ruled out from the enemy list.
Tao’s arrival and revelation of the extent of his knowledge on the agents and their secret modifications manages to persuade them to a negotiation. A deal is formed between the two parties: RK and KSA agents that they will co-operate with each other regarding the Union and keep their secrecy regarding each other.
DA-5 vs Cerberus
When Sangeen gets found out by the Cerberus members, the RK team sets to help them out. Takeo provides M-21 with a long-range back-up while Tao co-ordinates the battle against Ked. Takeo’s special nerve-damaging bullets gradually take toll on Ked. However, Lutai finds out Tao and he has to cut out communication with his teammates to concentrate on his own battle. Takeo faces quite a dilemma deciding on which friend he would go to help. Regis arrives and assures Takeo to help out Tao as he will take care of M-21’s fight. So, Takeo joins Tao and the two of them manage to bring down Lutai. Then they depart to help out M-21 and Regis but is caught and overcome by Taze.
The 12th Elder Arc
Takeo is mostly unconscious throughout this arc and wakes up to find the 12th Elder physically transformed having assumed a bat-like appearance. Rai annihilates the Elder and they all return home.
Throughout this arc Takeo accompanies Tao in keeping watch over the doubtful actions of the fugitive of Union who is brought in the house according to M-21’s request as he appears to be M-24.
Takeo joins Tao in planting false evidences to direct the investigating Elders against Crombel. But they are caught by Yuri and Bonerre when they arrive in the old base to plant the false evidences.
Tao and Takeo
Takeo along with Tao is chained and beaten up by Yuri (who is enraged for their rejection of his fancy for Seira), while Rai and team finish off the two elders. Frankenstein and Seira arrive to rescue them with Bonerre being forced to lead the way. Yuri escaped in time as the rescuers have arrived. However, Bonerre enacts self-destruction to injure Tao and Takeo mortally. The wounded duo is brought home where the destroyed lab leaves no chance of their treatment. Rai steps in to revive them despite his own gravely deteriorating health. Both Tao and Takeo are awakened by Rai and gradually heal their injuries.
Traitorous Clan Leader Arc
The trio convinces Frankenstein to train them while Rai has entered a temporary hibernation. The RK team take-off with Tao piloting the helicopter to Frankenstein's Island. During training, despite attempting different group attack formations, they fail to land a single attack on their trainer, Frankenstein. Irritated at the repeated outcome, they suddenly get the alarming news from KSA about the arrival of more Union elders. They quickly depart for the city. Frankenstein leaves them once they reach the city skies as they are told to head home.
The RK team reaches home and M-21 receives a call from M-24 aka Mark telling to bring the rest of the data to the school alone threatening to kill the children.
Takeo joins M-21 and Regis and head towards the school with fake data prepared by Tao, planting sensors as soon as they reach the grounds as Tao has instructed. He and Regis help take away the children from the assassins and leave M-21 to hold off the pursuers while they hide the children. They return as soon as they could to help out M-21. Takeo takes on Yuri while M-21 faces Mark and Regis fights Kalvin. But they fall for Kalvin’s trick and end up taking poison to get antidote for the children. Suddenly Rael appears and saves them (under Tao’s manipulation) as well as getting the antidote and killing Kalvin. Yuri and Mark flee and everyone returns back home, bringing with them the unconscious children.
Takeo accompanies Tao to Roctis' Island (after Seira is kidnapped by Ignes) to get back Rai and others. He snipes down two choppers pursuing them.
Afterwards, the trio are joined by Karias on their way to a meeting with KSA which gets cut off by the presence of 3rd and 5th Elders. Karias advises them to leave and they do so. However, they are caught midway by Kentas. A fight breaks between Kentas and the trio. Takeo and Tao do their best to fight the werewolf by themselves as M-21 is overwhelmed at the sight of a real werewolf. When M-21 reveals his transformation to defend himself, Kentas gets infuriated and is determined to erase him. Takeo attempts to divert Kentas' attention by attacking him in order to save M-21. Although Kentas finds his speed commendable, Takeo is easily defeated and about to be killed along with Tao. However, to both Tao, Takeo and their opponent's surprise, M-21 fully transforms to save his comrades.
As a member of the DA-5, Takeo was modified and trained in long-range combative skills. After joining Frankenstein's household, both he and Tao have asked Frankenstein to enhance their powers in order to increase their capability to protect their comrades, especially M-21, with whom they have formed a strong bond of loyalty and friendship.
He excels in marksmanship and long-distance combat, and was an excellent sniper for the DA-5 group. His skill is great enough to elicit surprise from his teammates in the rare event in which he misses his target. Takeo possesses incredible accuracy and faster-than-human reflexes with his weapon as he was able to destroy a falling lamp without turning in its direction. Takeo uses a large sniper rifle that is carried in a massive casket. Even without his rifle he is accurate with his other weapons, as shown through his expert use of his pistols against various enemies.
Takeo is known for his excellent vision, as he was able to accurately shoot and kill a man from at least several kilometers away in one shot.
Takeo possesses considerable physical strength, able to swing his huge weapon case around during first battle with Frankenstein and using it to block Frankenstein projectile attacks. Takeo has been shown to be remarkably fast, especially when he consumes D. His speed increases to the degree that takes a casual Frankenstein by surprise. After experimentation by Frankenstein, his speed has increased further; now being able to fight on par with the Cerberus member Lutai and even managing to stop his high speed rotation by clashing with him at an equally high speed.
Like his fellow mates from the DA-5, Takeo can use D (three levels of a stimulant drug: a lesser effect [30%], a destabilizing one [100%], or a last resort [200%]) to temporarily boost his physical strength.
After the implantation of a portion of Dark Spear into his body, his physical and spiritual abilities are increased dramatically. To trigger its effects, he partially covers his body with the aura of Dark Spear and part of his skin turns to dark purple. By using much more power, he can increase the effects of Dark Spear. He gains two-bladed knuckle-like weapon from dark aura after activating second stage of this power. However, like Frankenstein he loses his control slowly.
Dark Empowerment: Takeo can imbue his regular bullets with the energy of darkness from Dark Spear. He is able to pierce a strong werewolf (Urne) by this technique.