Manga Volume 12

 is the twelfth volume of the manga adaptation of That Time I Got Reincarnated as a Slime. The special edition of this volume is bundled with an OAD.

Synopsis
AN INEVITABLE CRUSADE

With the help of Queen Ramiris, the children are now in stable condition and should lead normal lives, much to Rimuru's relief. But all is not well... In fact, there are forces of humankind in this fantasy world that do not look kindly upon a slime-led nation of monsters. And now, insidious threats to Rimuru and the country of Tempest may be lurking around every corner!

Chapters

 * Chapter 53: Mjurran the Witch
 * Chapter 54: Prelude to Calamity
 * Chapter 55: Natural Enemy of Monsters
 * Chapter 56: Entangled Intentions
 * Chapter 57: Bringer of Misfortune
 * Chapter 58: Disaster

Bonus Short Story:
 * Veldora's Slime Observation Journal: Defeat