Light Novel Volume 9/Synopsis

Prologue: The Waves of Another World
Naofumi fought in a Wave together with Kizuna's friends, successfully fend it off and evacuate the village where it happened. After the Wave, Naofumi reminds that his mission in this world is to punish Kyo and bring the Spirit Tortoise's stolen energy back to his world.

Chapter One: Otherworldly Techniques
Naofumi met Alto, a friend of Kizuna. Alto whine about how the recently summoned heroes, vassal weapon holders and other countries in their world seems to underestimate the threat of the waves. Alto showed an ancient book to Kizuna that depicted cooperation between worlds. They then discussed about Kyo, the state of his expanding home country, and an inevitable war with them.

Chapter Two: Quick Draw
Naofumi went to the castle's training ground to hand over Raphtalia's sheath. Glass confirmed that despite having low prana, Rishia indeed have the talent to get stronger. Ethnobalt revealed to have stats growth similar to Rishia's, and then Naofumi motivates him to work hard like Rishia did. Naofumi handed Raphtalia's sheath which gave her a haste-like ability and handed Alto's book to Rishia for her to get some information from it. When he got Spirit Tortoise Heart Shield, Naofumi unlocked a technique similar to Therese's gem magic, so he asked Therese to teach him magic in order to learn how to use the technique.

Chapter Three: Lure
The next day, Naofumi and co. went to Ethnobalt's hometown. Based on what Ethnobald said, his race is likely to be the parallel version of Filolials. The party took off to their original destination, a labyrinth for leveling up to prepare for the coming battle with Kyo. The following day, after the leveling, the party went back to the castle to resume Raphtalia and Naofumi's sword and magic training. Filo unlocked two fowl forms from previous level ups and gained an ability to sing which seems to affect Raphtalia and Naofumi's performance. Done with the training, they went to sleep.

Chapter Four: Like a Charging Wild Boar
In the middle of the night, Naofumi and co. awoken by a sound of explosion. Downstair, a girl named Yomogi enter Kizuna's house, claiming to came on behalf of Kyo to punish vassal and holy weapon holders. She uses a strange sword made by Kyo and proven to be a quite formidable opponent. After a prolonged fight, Rishia disarmed Yomogi with an ofuda, but something like vine shot from the sword and wrapped itself around Yomogi's arm, took control of Yomogi's body. Kizuna used her ability and succesfully helped Yomogi drop the sword. Naofumi and Glass then careened the sword out of the house before it exploded. Rendered harmless without a weapon, Naofumi captured Yomogi.