Light Novel Volume 21/Synopsis

Prologue: Use of Floating Weapons
After celebrating the victory against Piensa, Ren asks to train with Naofumi. However, this time Naofumi was asked to fight with floating shields as if they were swords. Apparently Ren's earnest training has made some progress as he was easily able to take on multiple floating weapons. During the duel, Eclair, Raphtalia, and Fohl observe and make comments on Naofumi's fighting style. In the end, Ren lost the duel due to his tunnel vision. Ren then reveals that he asked Naofumi to fight that way to emulate a powerful opponent from a game he played in the past. However, it seems to Naofumi that Ren has created his own version of the most powerful enemy in part of his motivation to get stronger. After some musing, Ren returns to blacksmith and Naofumi heads to Siltran.

Chapter One: The Siltran Situation
As Naofumi walks through Siltran, he spots Keel and the residents of Lurolona Village helping out and trading with the Siltran people. Even the children protected by the ancient hero Mamoru were helping out. Entering the castle courtyard he finds S'yne making progress learning how to sprout energy wings from R'yne. He is then directed to Mamoru who is already in a meeting with Melty and Ruft.

Entering the meting, Naofumi is debriefed on the political situation. Their victory against the mighty Piensa had made the small nation of Siltran seem like a mighty force. While other nations are now hesitant to attack Siltran, it seems like Piensa is trying to ruin Siltran's reputation. Now that Naofumi was seen in the battle against Piensa, it is also useless to keep his identity as a Hero hidden. Finally, they discuss the Bow Hero and hypothesize that Piensa is using someone he cares about to keep the hero on their side. After the meeting, Naofumi went back to the town to help Keel and the others with their work.

Chapter Two: Wagon Travel with Keel and the Gang
After a successful time trading in Siltran, Naofumi decides to move to begin trading outside of the Siltran castle town. After Keel teases Naofumi about his relationship with Raphtalia, Naofumi decides to bring her on the trip, along with Cian, Raph-chan, and Imiya. While Chick is pulling the cart, Naofumi bonds with the other children - teasing Keel and getting the know the usually guarded Cian. Eventually, they are able to make it to the remote village where they were able to trade and gather materials. As the party are hunting monsters, they are suddenly attacked by a wave of deadly creatures. The party seemed able to hold them off, but once a two-headed monster like the Cerberus appeared, Keel started to panic and the group retreated.

Chapter Three: Wave Trauma
After retreating to safety, Naofumi tries to determine why Keel went berserk. It seems that Keel, and likely other village children, have leftover trauma from the first wave. Any multi-headed monster might remind them of when their village was originally destroyed. Realizing that this might be a wide-spread issue, Naofumi decides that he needs to help the village children heal from the trauma. Returning to the village, he confirms his suspicions that it is a widespread problem and consults Rat for therapy options. In the end, the affected villagers decide to undergo dream therapy.

After figuring out a path forward, Naofumi goes to Raphtalia to stroke her head (after explaining and getting permission). Later on, Raphtalia gives him permission to stroke her tail.

Chapter Four: Thanks to the Assassin
A few days later, Mamoru arrives in the village. Apparently, they were able to find the pacifier from Q'ten Lo which seems to be one of Raphtalia's ancestors. After a few preparations, they teleport to a neighboring nation where they find her over a recently killed fox-demon like Tulina. After the accompanying Water Dragon killed the corrupted king, the heroes and pacifier flee the nation.

After catching a breath, the two groups introduce themselves. The ancient pacifier introduces herself as Natalia. Unfortunately neither Natalia nor the Water Dragon know anything about to get back to the modern-day. After a brief conversation, the pacifier and her dragon decide to inspect Lurolona Village.

Chapter Five: Genetic Modification
As the group head towards Lurolona Village, they talk about the role of the Heavenly Emperor of Q'ten Lo and the sealed monsters they have put away. They give Natalia and the Water Dragon a tour of the village and as they do so they learn that Keel has gone missing. Arriving at Rat's lab, they learn that Holn may be responsible for Keel's disappearance so they enter inside. As they travel further, they notice that Holn has made several changes to the lab, including a secret basement lab.

Suddenly, the ground shakes. As the group heads back outside, they notice several towers growing out of the ground. In order to unlock the lab, someone has to climb on top of each of the seven towers.

Chapter Six: Mikey
At the front of the lab a barrier prevented anyone from entering. After teamwork and significant effort from Natalia and the Water Dragon, a small force is able to pass through. As they travel through the new addition, they find several interesting experiments including a humongous Raph duplicate made of slime. After some fighting it is revealed that the Raph duplicate is Rat's beloved monster Mikey. At a critical moment of decision between saving Mikey or Keel, Naofumi asks to speak with Keel before she makes a decision. Surprisingly, Holn accepts and allows them through.

Chapter Seven: The Raph Species Upgrade Plan
Naofumi and his party continue into the lab as they hypothesize what type of research Holn is conducting. They find Holn who then points them towards Keel. As they try to talk down Keel from being "modified", she reveals that while the therapy is working, it's not actually improving her current condition. To that end, she wants to get stronger so she has no reason to be scared. Talking to Holn, she describes her ability with the Vassal Whip to bring forth latent potential from a person's potential. In Demi-Humans like Keel, it can unlock the second transformation called Beast Transformation. Holn then decides to give Keel a "trial run" of different possible "upgrades" through illusion magic. However, in the end, since Keel would be unable to revert the beast transformation everyone decided to indefinitely postpone the operation. Holn then gives Naofumi a rare material which was used to unlock several shields. After Holn reverses the transformations done in the village, Natalia chastises her and the Vassal Whip spirit.

Chapter Eight: The Troubles of the Shield Hero
Information to be added later on.

Chapter Nine: Confusion Target
Information to be added later on.

Chapter Ten: Filolia
Information to be added later on.

Chapter Eleven: The Imitations (Improved)
Information to be added later on.

Chapter Twelve: The Origin of the Waves
Information to be added later on.

Chapter Thirteen: How to Kill a God
Information to be added later on.

Epilogue: The Fear of Those Who are Eternal
Information to be added later on.