No Game No Life, Vol. 9 (light novel)

All"™s fair in love and war! Gamer siblings Sora and Shiro have at last defeated the Old Deus Holou, and now they''re switching gears: Their next endeavor is to make Holou the number one pop idol in all of Disboard! They"™ve even abandoned their royal posts, halting all domestic affairs to focus on her training. But amidst the chaos of their pet project comes a strange message from the representative of the tenth-ranked race, the Ex Machina. . Is another arduous battle on the horizon for Sora and Shiro?!