Spirit Turtle Arc

The Spirit Turtle arc is the eleventh arc of the Light Novel and Web Novel of The Rising of the Shield Hero.

Synopsis
A mysterious force of nature has been rampaging throughout the world. Naofumi and his party must stop this unknown beast in order to save the world.

Summary
In the aftermath of the fight with the other-worldly heroes it becomes painfully clear how the Heroes need to become stronger. Naofumi is given access to Melromarc's stockpile to use the different power-up methods and Queen Mirellia arranges for combat advisors to train the four heroes. The heroes are introduced to Eclair Seaetto, (a sword wielder who now governs the area around Raphtalia's Village) and Elrasla Grilaroc, the last practitioner of the Hengen Muso combat style. Even though these combat advisors are shown to be effective and Eclair even beats Ren in a duel despite not being a hero, Ren, Itsuki and Motoyasu try to skip out of the training sessions. However, Naofumi's team - especially Rishia - start to learn about Hengen Muso. With the Heroes repeated trying to skip out of the training sessions, the queen negotiates with them and allows them to leave if they investigate rumours about mysterious attacks around the world.

Naofumi and his party are eventually assigned by the Queen to also look into these rumours. They head to Lerno Village and find it overrun by parasitic familiars. Naofumi's team is able to fend off these familiars however Keel is almost taken over by their parasitic abilities. Back at the castle, Melromarc's shadows have gained enough information to find out that the mysterious beast on the rampage is a Guardian Beast called the Spirit Tortoise and the monsters attacking around the world are its familiars. Naofumi and his party hurriedly try to rush to an eastern country where the Spirit Tortoise resides.

Arriving in the eastern country, Naofumi finds the surrounding area in utter devastation. Many people have died and the three other heroes have gone missing. Attempting to stop the Spirit Tortoise in its tracks, Naofumi, Raphtalia, Filo, Eclair and the Hengen Muso lady attack. After a hard-fought battle, the Spirit Tortoise is beheaded and the defence-force celebrates their victory. Climbing onto the back of the Spirit Tortoise, they find a temple with a warning from the previous hero about the Spirit Tortoise. Naofumi then starts the search for the missing heroes were investigating into the Spirit Tortoise.

While fighting a hoard of left-over familiars, Naofumi and his party are confronted by Ost who claims to be a familiar of the Spirit Tortoise. She says that the Guardian Beast is not dead and it has been corrupted by some unknown force. Soon after, they find that the Spirit Tortoise has been regenerated with a new, terrifying form and is now headed straight for Melromarc. Naofumi and his party attempt to slay the Spirit Tortoise or at least attempt to slow it down but all efforts seem useless. Eventually, Fitoria arrived to help in the battle. She agrees to fight the main body of the Spirit Tortoise while Naofumi and a portion of the defence force infiltrates into the interior of the body. They determine that they need to destroy the head and the heart at the same time to truly defeat the Spirit Tortoise. After a failed attempt and a harrowing effort, they are able to destroy the head and seal the heart at the same time to stop the Spirit Tortoise for good. Naofumi and his party travel further into the Spirit Tortoise to find who has been corrupting and manipulating this Guardian Beast.

Entering the core chamber, they find the other three heroes captured and the Spirit Tortoise's energy being siphoned by a villain calling himself Kyo. When it seems like Kyo was too powerful to be defeat, L'Arc, Therese and Glass show up to also defeat the villain. The two groups work together and fight the evil Vassal Book wielder. It is only because of Ost helping Naofumi cast Liberation-class magic and Rishia hidden abilities the heroes were able to defeat Kyo and destroy the Spirit Tortoise core. Kyo takes the remaining energy gathered by the Spirit Tortoise and then flees through a portal to his own world. However, with the Spirit Tortoise's core destroyed, Ost (the spirit of the Spirit Tortoise) starts to fade away. She gives a solemn goodbye with Naofumi's party and then asks them to return the Spirit Tortoise's energy back to their world. If they are successful, this will increase the time before the next wave. As a final gift, Ost gives Naofumi a special exception as a Legendary Hero which allows him to travel between worlds. With her death, Naofumi, his party and L'Arc's party travel through the portal to try to capture Kyo.

Volume 6

 * Chapter 4: "Custom Order"
 * Chapter 5: "Battle Advisors"
 * Chapter 6: "Hengen Muso Style"
 * Chapter 7: "Impossible Training?"
 * Chapter 8: "Life-Force Water"
 * Chapter 9: "What it Means to Train"
 * Chapter 10: "Kigurumi"
 * Chapter 11: "——'s Familiar"
 * Chapter 12: "Getting Ahead of the Enemy"
 * Chapter 13: "Game Knowledge Bares its Fangs"
 * Chapter 14: "What it Means to Be a Hero"
 * Chapter 15: "The Spirit Tortoise"
 * Chapter 16: "The Country Above the Spirit Tortoise"
 * Epilogue: "A Disquieting Place"

Volume 7

 * Prologue: "The Search"
 * Chapter One: "Helping Others"
 * Chapter Two: "Spirit Tortoise Familiar (Human Type)"
 * Chapter Three: "The Spirit Tortoise Reawakens"
 * Chapter Four: "Spirit Tortoise Tyrant"
 * Chapter Five: "Mass Destruction"
 * Chapter Six: "Versus the Spirit Tortoise
 * Chapter Seven: "Buying Time
 * Chapter Eight: "The Search"
 * Chapter Nine: "The Spirit Tortoise Cave"
 * Chapter Ten: "Strangers"
 * Chapter Eleven: "The Heroes' Inscription"
 * Chapter Twelve: "The Spirit Tortoise's Heart"
 * Chapter Thirteen: "Who Pulls the Strings"
 * Chapter Fourteen: "Liberation"
 * Chapter Fifteen: "The Spirit Tortoise's Soul"
 * Epilogue: "Ost Horai"

Web Novel

 * Chapter 116: Blue Sand Sound
 * Chapter 117: When Game Knowledge Betrays You
 * Chapter 118: The Spirit Turtle, Recon Battle
 * Chapter 119: Strategic Countermeasures
 * Chapter 120: Stalling for Time
 * Chapter 121: The Message from the Hero
 * Chapter 122: Exploration
 * Chapter 123: Blue Hourglass
 * Chapter 124: Heart of the Spirit Turtle
 * Chapter 125: Possibilities
 * Chapter 126: Versus The Spirit Turtle, The Final Showdown
 * Chapter 127: Overprotective
 * Chapter 128: A Hero’s Treatment
 * Chapter 129: Social Standing
 * Chapter 130: Level Reset

Character Introductions

 * Eclair Seaetto
 * Ost Horai (light novel)
 * Kyo Ethnina (light novel)