Después de su reencarnación de otro mundo, Setsu lleva una nueva vida como estudiante de secundaria. Sin embargo, por una razón desconocida, es convocado de regreso al mismo mundo, Eclair. Antes de que pueda disfrutar de su regreso, se ve envuelto en la guerra con los demonios que originalmente había acabado. Aunque sus viejos camaradas corren en su ayuda, también nota la magia de su viejo amigo en el campo de batalla. ¿Qué está pasando en el mundo de Eclair en el que Setsu entra por segunda vez?'

Setsu sets off for the demonic continent - and into a chance meeting with the granddaughter of a certain merchant he met once in his previous life, who has her own duty to fulfill...

Setsu, Ruri, and Levia arrive on the demonic continent. They reconnect with old acquaintances and are swept up in a sinister plot involving the Demon Lord and a mysterious merchant.

The Demon Lord Dezastol reflects on the previous war and the promise of peace she made to Setsu. Meanwhile, Setsu, Levia, and Vlad rush to rescue her from the unwanted marriage to the mysterious Terran Sneeter.

While Setsu is fighting his battles on the demonic continent, Yuhi trains to become strong enough to stand by his side. With the help of Elka's tough love, she discovers her own unique kind of determination.

Setsu and Levia set off for the Beastmen continent. On their way, they cross paths with Setsu's old friend Alizee and discover she has been battling a mysterious dragon. Together, they unravel the shocking truth.

Arriving at the Beastmen continent, Setsu and Levia meet Shironeko, a fierce fighter. When Shironeko is asked to assassinate Setsu, she agrees for the sake of her ill sister. All is not what it seems, though, and Setsu uncovers a tangled web of deceit.

Setsu meets more old allies in the Beastman capital, reuniting with the King Regulus and his daughter Roa. Old rivalries run hot, and Setsu finds himself in a duel that isn't what it seems...

Yuhi reaches the demonic continent alongside the kingdom's forces as both sides ready for a fight. With Setsu still missing on his adventures, they face a desperate battle to hold the line until he arrives.

The final battle gets serious with Setsu's arrival. With his friends old and new alongside him, Setsu is certain they can be victorious and save this world for a second time.

After the defeat of the main forces of Toma, he himself appears to end the world, as he has announced.