Eve of War

Eve of War (開戦前夜) is the twelfth volume of the That Time I Got Reincarnated as a Slime Light Novel.

Synopsis
Threatened by Tempest’s rapid expansion, the Eastern Empire finally begins to strike back. According to Chloe, the time-traveling Hero, there exists a timeline in which the Empire defeats Rimuru and Tempest subsequently collapses. While Rimuru’s doom isn’t set in stone, his victory isn’t a foregone conclusion either. And to make matters worse, an Empire spy seems to have infiltrated Tempest...

Chapters

 * Prologue: The Jesters' Escape
 * Chapter 1: The Sound of Soldiers' Boots
 * Chapter 2: Accomplishments and Preparation
 * Interlude: A Look Inside the Empire
 * Chapter 3: The Imperial Guests
 * Chapter 4: The Empire Makes Its Move
 * Chapter 5: Toward the Opening of Battle
 * Epilogue: The Emperor's Conquest

Adaptations
This volume was adapted into the following material:

Manga:
 * To Be Added.

Anime:
 * To Be Added.