It's been roughly one year since Chūya Nakahara joined the Port Mafia, and he's got his sights set on an executive position. But as he makes plans to move up, a man by the name of Paul Verlaine—claiming to be his older brother—appears and vows to assassinate everyone he cares about! Now, Chūya must team up with Adam, a European A.I. investigator, to stop this lunatic before the storm swallows Yokohama once again…