Doppo Kunikida vs. Blond Guy

Doppo Kunikida vs. Unnamed Blonde Guy is a battle fought between Armed Detective Agency member Doppo Kunikida and an unnamed blond guy who is part of an underground criminal organization affiliated in the organ-trafficking syndicate.

It happened at an isolated military base during the Agency's investigation on the Azure Apostle messages and, concurrently, as part of Osamu Dazai's entrance exam.

Prologue
After receiving a message from the Azure Apostle that requests the Agency to prevent passenger airline flight JA815S from crashing into Yokohama, Kunikida and Agency rookie Osamu Dazai track the transmitter signal paralyzing the aircraft to a former National Defense Force military base. Upon arriving, their vehicle is immediately attacked by armed men. Kunikida then materializes and tosses a flash grenade from his notebook at them, giving Dazai a chance to head to the building's maintenance depot inside.

After neutralizing the armed men, Kunikida set out to follow Dazai, though he is clueless as to where he went nor where the transmitter signal is located. Upon hearing glass shattering somewhere inside, Kunikida thinks that Dazai might be fighting with the enemy and instinctively brings out his pistol. He stakes the first floor, only to find it vacant and having merely been used for storage.

Battle
Kunikida sets out to the second floor, but he suddenly feels an unbearable sensation and notices the number "39" etched throughout his skin. A young man then taunts him and remotely slams him with his offensive long-range number ability onto the ground and walls. Afterwards, Kunikida notices his number reducing, which he figures out shall cause death when it reaches zero, similar to how their initial suspects – the cabdriver and Zadkiel Alamta – died with the digits "00" marked on them.

With his opponent having emptied his pistol's magazine, Kunikida attempts to engage the young man in close combat. However, the man's ability proves to overpower him even if he tries to evade it, as the man explains that he controls him with the number on his body in any direction he wishes. Kunikida is repeatedly swished on air and slammed to the ground, acquiring him various internal and external injuries.

The young man is exhilarated with the thought of finally working underground with ease when he defeats Kunikida and the Agency, though Kunikida remains steadfast in preventing him and his group from selling any more organs and weapons. Kunikida tries to distract him into talking while he attempts to write on his notebook, but he is again accelerated into the air when the man notices his scheme and rids Kunikida of his notebook.

As the young man rams Kunikida onto the ground once more, he takes out the release key for the communicator and snaps it in half, delightfully scorning the detective. Kunikida notices a bleeding and beaten Dazai up the operations room on the second floor, whom he locks eyes with. As the two call out to each other, Kunikida pulls out the wire gun on his waist and shoots at Dazai's direction, while which the latter leaps out the window. Using the tensile force on the wire, Kunikida glides through the air and switches places with Dazai.

Aftermath
Kunikida lunges into the operations room and faces Dazai's opponent, a tanned giant man with brass knuckles. As the latter swings his fist at him, Kunikida uses the man's momentum to throw him into the air over his shoulder. The big man stands back up and tries to land a second punch, but Kunikida swiftly grabs his wrist and throws him along the wall then into the ceiling.

The man repeatedly charges at Kunikida only to fail every time, as the detective tosses the man using his own momentum and uses his own strength against himself. Eventually, Kunikida hurls the big man out the window, who lands down the first floor utterly defeated and rendered unconscious.

Kunikida checks his body and finds the numbers vanished, thinking that Dazai must have defeated the young man below. As the two regroup at the operations room, Dazai shows the broken release key to Kunikida and panics. Kunikida appeases his concern and takes out an emergency spare page in his hip pocket. Kunikida then replicates the release key, which greatly astonishes Dazai.

After Kunikida presses the disable button to return the airplane's controls, Dazai calls the pilot, though they find the airplane at a relatively low altitude. The pilot eventually manages to regain the plane's altitude, resulting to Kunikida's and Dazai's mission success.

Light Novel and Anime Differences
Since the events in the anime take place after his entrance to the Agency, Atsushi Nakajima accompanies Kunikida and Dazai to the military base. Kunikida then instructs him and Dazai to head to the operations room, before he eventually battles the number ability user.

In the anime, Kunikida uses his ability to manifest a wire gun to shoot at Dazai's direction to switch places with him, rather than using the wire gun tucked on his belt from his previous battle as depicted in the light novel. Moreover, the last number marked on Kunikida before switching positions with Dazai ("04") is not shown in the anime. In general, the fight is quite shortened in the anime, relatively minimizing Kunikida's injuries and the intensity of such wounds.

Unlike in the light novel where Kunikida engages the big man much longer, tossing him repeatedly until he hurls him out the window, the anime depicts Kunikida apparently flipping the man in one swing, which ends in the big man's defeat.