Detective Masaki Shiiba must work the dangerous streets of Kabukicho, Japan's largest red light district. When an increase in gun crimes forces Shiiba to work undercover, he must forge an alliance with an "S" or spy, who turns out to be an influential man from the Matsukura Group. But when Shiiba gets a call warning him about his S-seeds of doubt are planted. If he can't trust his S, who can he trust?