Acid Town, Volume 3 (manga)

In a run-down city riddled with poverty and gangs, survival is a daily struggle for Yuki and his best friend Tetsu. In a desperate attempt to pay for Yuki's ill brother's hospitalization, the two of them get caught trying to break into the vault of the Seidoukai— an infamous yakuza group. However, Yuki catches the eye of the gang's young boss, Kazutaka Hyoudo, and the two of them escape imminent death after striking a deal.

Hyoudo is willing to take care of his brother's hospital bills— for a price. A weekly visit to the Seidoukai office doesn't seem like much to pay, but the boys' connection to the criminal group has already begun to draw the wrong kind of attention. As tensions between rival gangs come to a head, a shady, malicious figure from Yuki's past drags him back into a tangled web of extortion and underworld deals and Yuki finds himself left with no choice but to return to old and painful methods of survival just to get by. But is he truly as alone in the world as he fears? In this dark time, Hyoudo's true connection to Yuki is revealed...!