Light Novel Volume 9/Synopsis

Prologue: The Waves of Another World
Naofumi fought in a Wave together with Kizuna's friends, succesfully 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: Otherwordly 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 a cooperation between worlds. They then discussed about Kyo, the state of his expanding home country, and an inevitable war with them.