That Time I Got Reincarnated as a Slime, Volume 8 (manga)

After his humiliating defeat at the hands of Milim, Demon Lord Carrion's follower Phobio seethes with anger. His negative emotions make him a perfect vessel for the legendary Charybdis, so Footman and Tear of the Moderate Harlequin Alliance pay Phobio a visit in the hopes of summoning the grand beast. Before long, Rimuru receives a report that Charybdis has indeed come to life, and is heading for Tempest. Where f irst there were just rumors of this conspiracy, now there's the telltale smoke of an approaching battle...