Atsushi Nakajima is a starving runaway with nowhere to go after being brutally cast out of his orphanage and left to die on the streets of Yokohama. His desperate plan to rob the next passerby goes awry when he instead saves a whimsical, bandage-wrapped detective named Osamu Dazai from a suicidal plunge into the river. This fateful meeting drags Atsushi into the supernatural underbelly of the city, also known as *Bungō Sutorei Doggusu*, where he discovers the shocking truth behind the "man-eating tiger" that has been haunting his footsteps: the beast is actually his own uncontrollable ability. Recruited into the Armed Detective Agency a specialized group of "gifted" individuals with powers inspired by literary legends Atsushi must grapple with the deep-seated trauma of his past while navigating a world where his very existence has suddenly become a lethal commodity.

The stakes skyrocket when Atsushi learns he has a staggering seven-billion-yen bounty on his head, making him the prime target for the ruthless Port Mafia and the wealthy international organization known as the Guild. As the city becomes a battlefield for these warring factions, Atsushi is thrust into a fierce rivalry with the merciless Ryūnosuke Akutagawa, whose murderous shadows force the young boy to confront his own self-loathing. Amidst the mind-bending supernatural duels and shifting loyalties, he is haunted by the internal struggle of whether a "stray dog" like him truly deserves a place to call home. Driven by an unwavering desire to prove that his life has worth, Atsushi vows to master the beast within and protect the found family that gave him a second chance, no matter the cost.