Teruko Ōkura vs. Sigma

Teruko Ōkura vs. Sigma is a battle fought between Hunting Dogs vice commander Teruko Ōkura and the Sky Casino manager Sigma during the hunt for the Armed Detective Agency who are accused of terrorism.

It happened at the Sky Casino, coinciding with the Decay_of_the Angel' terrorist plot, specifically occurring sometime between their second and third phases of terrorism.

Prologue
The Hunting Dogs acquire a lead that the Agency members Atsushi Nakajima and Kyōka Izumi and their ally, Lucy Maud Montgomery, headed to the Sky Casino. Teruko and Michizō Tachihara are then dispatched to the airborne casino and instruct Sigma to close down the casino while locating the terrorists. Not wanting his casino's affairs to be put on hold, Sigma refuses to blockade the casino, prompting Teruko to trigger an explosion within the structure to forcibly close all the casino's exits.

Sigma exhausts all possible feats and methods he can to subdue the Hunting Dogs, though to no avail. Eventually, Teruko confronts Sigma in the telecommunications room to have him surrender and to destroy the transmission machine that would trigger various RDG1800 explosions, but Sigma remains unwilling to give up on his casino.

Battle
Sigma notes that the transmission machine's detonation signal can be overridden by a key, which he tosses to Teruko. Determined to fight for his casino, Sigma brings forth the Painless Gun and fires a barrage of high-speed ammo. Teruko, with her enhanced strength, repels the bullets with her bare hands and soon attacks the turrets' muzzles with two kitchen knives.

Sigma attempts to take out a tablet to activate a new set of turrets, but Teruko kicks down his hand and prevents his plan. Cornering him, Teruko urges him to surrender, more so because he has no chance of winning ever since the start. Sigma agrees to how average he is from his conception until his present self; he then imparts a final statement that everything has gone as planned.

With his free hand, Sigma brings out his personal, modified directional resonance gun and pins down Teruko down the ground. He indignantly fires at her, triggering an intracranial-affected resonance five times the usual output. However, Teruko stands back up and provokes him, much to Sigma's disbelief. She then rushes towards him and grabs his resonance gun; Sigma also notices wounds in her ears, deducing that she must have gauged out her ear canal as a countermeasure.

Teruko explains that the Hunting Dogs undergo rigorous and inhuman procedures to achieve their enhanced physical bodies, all for the sake of embodying utmost strength in preserving the country's order. As she breaks his resonance gun, Teruko chokes Sigma and breaks him through the wall, holding him at the edge of the casino. For the last time, she orders him to surrender; wanting to protect at least the casino over himself, Sigma grabs Teruko and jumps off the edge of the casino.

Initially in a bind in grappling with Sigma while falling, Teruko manages to break free from his hold and grabs on a ledge. Meanwhile, to her shock, Sigma is saved by Atsushi, and they land on an electric power installation box, where Atsushi interrogates Sigma through Ango Sakaguchi.

Aftermath
After Atsushi saves Sigma, Ango exposes Sigma of wounding Santōka Taneda prior the terrorism's outbreak. Sigma finally yields and agrees to cooperate with them. However, Nathaniel Hawthorne arrives and launches an attack, compelling Atsushi and Lucy to launch a counterattack against their troublesome opponent. In the end, Sigma releases himself from Atsushi's hold and falls from the casino.

Meanwhile, Atsushi saving Sigma appeared to the Hunting Dogs as further incriminating evidence of the Agency saving their fellow terrorists. As a result, Teruko assigns Tachihara to infiltrate the Port Mafia once more to gather more intel to ultimately capture the Agency, though he is reluctant to heed her orders upon realizing that the Agency could not be terrorists.