Teruko appears as a short, young girl wearing the standard Hunting Dogs uniform, albeit the hat sports enough space for her hair. Her hair is light, long, styled in a wavy ponytail and tied with what appears to be a large ribbon. Befitting of the Mad Dogs, she has a sword by her side.
Teruko is intense and boastful. She revels in her power and role among the Hunting Dogs. She has a significantly short fuse and easily intimidates strangers after the initial shock of her youthful appearance disappears. She is aggressive when angered or provoked.
Her temper is so extreme that she regularly threatens violent action against people who oppose her, involving evisceration and gutting. Lower-ranked authorities refer to her as the blood-briar queen, a member infamous for her bloodthirst and feared even by her allies, she uses a steel whip as her main weapon. She also seems to have an abnormal obsession with Ōchi Fukuchi.
Befitting as the Vice-Commander of the Hunting Dogs, Teruko takes her duties very seriously even if she enjoys the experience of battle along the way, often seen laughing in joy as she takes down her opponents. She considers herself a "Protector of Justice" and gladly continues to engage in combat even when heavily injured, stating that is what heroes do. Teruko takes pride in her status as a Hunting Dog member as she described the Sigma about how a Hunting Dog is a "slave" to society and the "ultimate violence" above all that is necessary to maintain the nation and the world's order and peace and that she would gladly sacrifice her own body and soul via being required to undergo monthly maintenance surgeries and fight to the death for the sake of the people.
Teruko's ability, Gasp of the Soul (魂の喘ぎ, Tamashī no Aegi?), allows her to manipulate the age of anyone she touches. Teruko herself mainly uses her ability for interrogation and torture, enabling her to rapidly age someone to old age and cause them to develop several illnesses and maladies normal to old people. She would then rapidly pull them back to a much younger age, putting a severe psychological strain on her victims' senses and severely damaging them mentally due to how quickly she alters their age before they can acclimate to the new sensation and feelings of their rapidly changing bodies. This makes her ability ideal for interrogations despite her not actually "hurting" her victims.
Other than this Teruko has also displayed the ability to use her ability on herself, allowing her to alter her physical age for both disguising herself and to mature her body to a more physically stronger age.
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Teruko's rocket is the last to land of the Hunting Dogs, with her furious she can't get out, demanding blood and expressing her endless bloodlust. After Saigiku Jōno frees her, she claims she would have pruned everyone's limbs like bonsai trees - a hobby she partakes in.
Jōno attempts to brief her on the situation, but Teruko cuts him off, warning him not to 'read' her mood by listening to her heartbeat, as it will only anger her more, and she'll cut off his ears as punishment. Although this silences Jōno, it doesn't faze Fukuchi, who praises his squad and expects great success from them. Hearing his praise perks Teruko up, and she's more than happy to vow risking her life for him.
The Dogs discuss possible routes the Armed Detective Agency will take to try escaping the authorities. Teruko asks if there's more than two options, to which Jōno assures her there are no routes he isn't familiar with that the Agency would take. Musing which path the Agency takes, Teruko takes delight knowing that one wrong move could end in their demise, and she refers to them as "pitiful dogs", flashing a wicked smile.
Teruko instructs the group they will go both routes, tearing apart their enemy's schemes ahead of time as they always do. She and Fukuchi go the northern station route. Although the military only has one working vehicle, Teruko and the other Dogs depict superhuman speed, making a car unnecessary. She and Fukuchi are assigned to the northern station, while Jōno and Tetchō take the southern road.
Sometime during their operation, Teruko and her fellow Hunting Dogs are requested for dispatch having found the Agency, with Michizō Tachihara rejoining them as the undercover fifth Hunting Dog and cornering Akiko Yosano that leads to her arrest.
As Tachihara returns to the Hunting Dogs' headquarters, he sees Teruko crying after making a criminal confess within such a short period of time. During their meeting, Tachihara reports that the Agency has been last sighted two days ago at the bank, after which eyewitness reports have stopped coming. He wonders if they have gone overseas, but Teruko thinks that the criminals are still within the country and may have conveniently found a base and a leader. She also informs them that Fukuchi is going to meet with and destroy the enemy's boss.
After Jōno and Tetchō uncover intel that Lucy went to the Sky Casino, Teruko and Tachihara fly to the airborne establishment, who become suspicious of its nature that may be hiding the terrorists. She instructs casino manager Sigma to close down the facility to search for terrorists, specifically to blockade and seal every section of the casino until their targets are forced to surrender. Sigma declines upon seeing subsequent losses it may have on the casino and threatens the Hunting Dogs with his casino guards' directed resonance guns. As Teruko "obediently" abides by Sigma's terms, an explosion occurs that seals all the casino's exits, while Teruko revels that they shall now be able to search the casino without anyone allowed to leave.
As Teruko and Tachihara split up to search for the Agency in the casino, she soon arrives to help him in stopping an unmanned aircraft ram over them. Using her Hunting Dog-enhanced brute strength, Teruko manages to stop the aircraft, only for Tachihara to notice that it is full of RDG1800 coin bombs that all explode. Nonetheless, their teamwork manages to save both of them from getting caught in the blast.
Tachihara tells Teruko his theory on the terrorists' next plan, which is to use the coin bombs to be circulated throughout the globe and ultimately cause indiscriminate slaughters. En route to the communications room to publicize the casino's plot, they are blocked by the casino guards, all of whom they engage and defeat. In a weakened state, Teruko finds Tachihara attacked by hotel guests after they discover a bounty placed on them by Sigma. Knowing that they cannot harm civilians, Teruko plots with Tachihara to escape from their pursuers.
She activates her ability that turns her into an old lady and Tachihara into an infant, escaping from the riot and heading to a restricted area. Using her ability to age a guard, Teruko asks for directions on how to take control on the communications room terminal, which is to take the key from Sigma. Hence, Teruko heads to Sigma to engage him and instructs Tachihara to keep the guards at bay. To her surprise, Sigma hands her the key to the terminal, before Sigma summons the high-velocity Painless Gun. Despite its rapidness, Teruko repels the gun's bullets with her brute strength and soon clashes with Sigma. Teruko corners and urges the manager to surrender, but Sigma announces that everything has gone as planned.
Sigma fires his personal directed resonance gun five times the standard, but Teruko gouges her ear canal to withstand the gun's effect. She breaks Sigma's weapon and pins him down by the edge of the casino, warning him to give up for the last time. Unyielding, Sigma grabs her down and grapples with her as they fall off the casino. Initially firmly restrained by Sigma, Teruko soon breaks free of his hold and grabs onto a latch, after which she witnesses Atsushi Nakajima save Sigma from the fall. Soon after, as global organizations caught word of the coin bomb terrorism plot, Teruko instructs Tachihara to infiltrate the mafia once more to acquire intel on the other two missing Agency members, but Tachihara soon hangs up on her.
Two weeks after Fukuchi's return from Standard Island aboard the Boswellian, Tachihara reports to his fellow Hunting Dogs about the bizarre infection-like incident within the Mafia, specifically with an inhuman Ichiyō Higuchi turning Gin Akutagawa and Ryūrō Hirotsu into her kind, as well as witnessing an undead horde of mafiosi. Though Teruko insults how idiotic he reacted, she believes his story, as it coincides with recent disappearances of various mafiosi. Jōno conjectures it might be terrorism using an ability, which Tetchō thinks is the Agency's next terrorist act.
However, Tachihara subtly implies that the Agency cannot possibly be terrorists after recalling how the detectives kept on mentioning being falsely accused numerous times. Hence, he requests them to allow him to reinvestigate the case. They turn to their commander for his approval, though Fukuchi rejects it, claiming that Tachihara's ability is needed in addressing the infection case. Nevertheless, after Tachihara opens his alternative plan using the flash drive he previously broke at the Sky Casino, Fukuchi reluctantly allows him to investigate, earning Teruko's envy with managing to get the commander's careful consideration of his plan.
- (To Sigma) "Without order, people 'built for violence' would end up standing above the population. A world like that would be garbage. Therefore, if the Hunting Dogs exercise the strongest power as society's servants… We are searing the flames of order into our own selves."
- The name Teruko means "bright, glorious, splendid, flame" (燁) (teru) and "child" (子) (ko).
- Teruko's surname Okura means "big, great" (大) (o) and "warehouse" (倉) (kura).
- Her author namesake was a student of the real-life Sōseki Natsume.