What?! A gang of surfers that kills and rob?! I didn't see it coming!
@Pyoro They didn't just kill some random people, they were probably yakuza, so I doubt they want the police investigating. And it didn't happen on a small island, it happened in the city, they fled to the small island.
And Kay and Darriah are most probably here because the guys that were robbed want retribution. So investigation there was, now it's time to pay.