No Game No Life, Vol. 12 (light novel) by Yuu Kamiya
It's been a year since Sora and Shiro came to Disboard, where everything is decided by games. That very world is about to be split in two, and the pair doesn't have a way to prevent it! As if things couldn't get any worse, Demonia picks that exact moment to make a grand appearance. Sora, Shiro, and the gang aren't exactly heroes...but they're heading to the supposedly unbeatable Demon Lord's tower anyway!??