No Game No Life, Vol. 12 (light novel) — Yuu Kamiya

TALK ABOUT BAD TIMING…
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 has no idea how to prevent it! As if things couldn't get any worse, Demonia picks that exact moment to make a grand appearance and threaten to obliterate Disboard. It'll take a hero to fight this despair with hope: Sora, Shiro, and the gang aren't exactly “heroes”…but they'll head to the supposedly unbeatable Devil's Tower anyway to save the day!