A mysterious organization known as "The Blue Moon of Salvation" has been doing ominous acts all over the world such as spreading curses and siccing a powerful dragon on a town. In order to stop their plot, Yuji battles against them, employing his monsters' powers. The slimes infiltrate their hideout, but what do they find in its innermost depths...? Yuji also tames a flying monster-the Slibird-and makes it join his party!