The spiny lobster Panulirus japonicus (von Siebold, 1824) has a rather restricted distribution in the northwestern Pacific, ranging from Japan to Taiwan and southeastern China. It has been hypothesized that the Japanese populations of this species share a common pool of larvae for recruitment, and that these larvae are transported by the Kuroshio Subgyre. However, it remains unclear how the populations around western Taiwan and southeastern mainland China are maintained, as they are outside the Kuroshio Subgyre. In this work, a final-stage phyllosoma and a puerulus of this species were discovered for the first time in Taiwanese waters and off the southern coast. An extended genetic analysis of the Taiwanese and southeastern Chinese populations of P. japonicus showed that they all share a common gene pool. The larval recruitment hypothesis for P. japonicus was therefore modified by suggesting that its late-stage phyllosoma or puerulus may reach further south to southern Taiwan, with the branch of Kuroshio Current accounting for the larval recruitment of the populations around western Taiwan and southeastern China.