Shun is a tattoo-clad 3rd generation orphan in China. Shun and two others assist the police in undercover investigations in the fictional town of Midori, where illegals live. "Quartet" is a serious and violent look at the underbelly of a society where people are treated as slaves and used as test dummies for illegal manufactured drugs. ~~ Adapted from the novel "Quartet" (カルテット) by Osawa Arimasa (大沢在昌).