A being hailed as godlike in YGGDRASIL, a walking world boss, whose single-handed devastation of entire guilds was commonplace. Dio Brando, that was the boy's name in this alternate world. Due to some unforeseen circumstances, he was reincarnated into this alternate world and became the top fighter of Ainz Ooal Gown, a guild in the then-hit game YGGDRASIL. "Really? I've traveled to the world of Ainz Ooal Gown?" Having become a top-tier figure in that world, what will happen after the Overlord storyline begins?