Finder Vol. 8 Secret Vow (manga)

Pain and pleasure collide when a sophisticated underworld boss crosses paths with a naive photographer hell-bent on bringing him down! 

Photographer Takaba Akihito takes on a risky assignment trying to document the illegal activities of the Japanese underworld. When he captures its leader—the handsome, enigmatic Asami Ryuichi—in the crosshairs of his viewfinder, Takaba’s world is changed forever. 

After Asami's subordinate Sudo betrays him, Akihito attempts to chase Sudo down, only to wind up captured and at his mercy. Sudo's fixation on Asami has only grown stronger with time, to the point of wanting him dead. But Sudo isn't the only threat: another enemy appears on the horizon, gunning for the power Asami wields!