Third Army Arc

The Third Army Arc is the twenty-fourth arc of the Light Novel in The Rising of the Shield Hero. This arc is light novel exclusive and does not appear in the Web Novel.

Synopsis
With the looming threat of an attack from members of the Third Army, including the overwhelming power of S'yne's Sister and the plentiful Vanguards of the Waves, the Heroes must prepare as best as they can against this threat.

Summary
Worried about how they were quickly overcome by S'yne's Sister during their last confrontation, Naofumi and the other heroes attempt to power-up as much as they can. Deciding that they need to learn how to nullify the enemy's nullification magic, Naofumi and the other heroes reluctantly decide to resurrect the Demon Dragon Emperor. This is successful and the Demon Dragon decides to ally itself with Naofumi and hints that the way to repel nullification magic lies in the origin of Glass' combat style. However, before they are able to leave, L'Arc's castle is attacked by S'yne's sister, Lesty, three Vanguards of the Waves and an experimental artificial behemoth. With the Demon Dragon's assistance, the heroes are able to defeat Lesty and one of the Vanguards of the Waves while the other two are captured. From the two captured, the heroes learn that the Vanguards of the Waves are similar to Heroes as they are reincarnated people from other worlds.

After quickly updating the forces remaining in Raphtalia's World, Naofumi and the others head to the country Glass was originally from. They meet Glass' Master and find various weapons able to repel nullification magic thanks to Shildina's oracle abilities and Glass' heritage. Afterwords, the heroes then travel to the Demon Dragon's country in search of more information. While there they meet Ren II, a vanguard of the wave, who attacks them. However, he is quickly defeated. Afterwards, the Demon Dragon powers Filo up as her new Heavenly King and the heroes are given access to the Demon Dragon's treasure room.

Soon after, the heroes receive reports of two separate attacks by the enemy - one at the nearby port and one in the Demon Dragon's country. The heroes split up and Naofumi ends up going to the Demon Dragon Country. While there, he confronts three Vassal Weapon wielders including Malty, the Legendary Ofuda wielder, S'yne's sister, and an artificial demon dragon. While the enemy is more powerful, Naofumi and team show skill and teamwork. They are also able successfully repel the buff-nullification magic which the enemy casts. During the battle, one of Malty companions stabs her in the back. She turns out to be Rino, one of Queen Mirellia's spies. With this betrayal, the enemy starts to be become overwhelmed. By the time they flee, Sadeena becomes the new Vassal Harpoon wielder and Shildina becomes the new Legendary Ofuda wielder. S'yne's Sister stays behind and shows that even with the heroes' new power-ups, she is still more powerful. However, Naofumi ends up actually damaging her and S'yne's Sister decides to leave.

With the enemy defeated at the Demon Dragon's country, Naofumi and his group head to the port where they find Itsuki and the others nearly done winning their battle. They were even able to capture Mald. Later that night, S'yne's Sister secretly finds Naofumi and warns him about the power of the organization behind the waves - the Third Army.

Volume 18

 * Chapter 10: Dragon of Ultimate Magic
 * Chapter 11: Volunteer Soldiers
 * Chapter 12: Double Reflection
 * Chapter 13: The Reborn
 * Epilogue: The Game Knowledge Pitfall

Volume 19

 * Prologue: An Exchange of Otherworldly Information
 * Chapter 1: A Visit to the Head Temple
 * Chapter 2: Holy Tool Grotto
 * Chapter 3: The Work of Men and Monsters
 * Chapter 4: A Visit to the Demon Dragon Castle
 * Chapter 5: Appraisal Camouflage
 * Chapter 6: A New Heavenly King
 * Chapter 7: The Demon Dragon's Treasure
 * Chapter 8: An Alluring Pudding
 * Chapter 9: Just to Make Sure
 * Chapter 10: The Importance of Anger
 * Chapter 11: Opposing Nullification
 * Chapter 12: Intelligence Operative
 * Chapter 13: Insensitive Individuals
 * Chapter 14: Megido Iron Maiden
 * Chapter 15: Defense of the Port
 * Epilogue: A Visitor Late at Night

Volume 20

 * Prologue: Believing Sloth Will Save the World
 * Chapter One: Prisoner Transport
 * Chapter Two: Training for an Obstinate Man

Character Introductions

 * Artificial Behemoth
 * Ciel
 * Ren II
 * Glass' Master
 * Vassal Harpoon Reincarnator
 * Legendary Ofuda Reincarnator