Mysterious monsters appear as Naofumi is preparing for the next Wave. At the same time they show up, the Wave countdown stops. The Queen summons the Four Cardinal Heroes, and tells them that the Spirit Tortoise has revived.

The leaders of all the nations’ militaries gather in the Spirit Tortoise Kingdom. Naofumi is there as well, and promises to offer his help as one of the heroes. But just before they decide on a plan, a mysterious woman appears…

The Spirit Tortoise begins its march once more, appearing at the border of the kingdom bearing its name. Naofumi volunteers to lure away its familiars while the army tries to bring it to the mountains. The Spirit Tortoise’s familiar, Ost, fights alongside the humans…

The Spirit Tortoise’s head was cut off, but Ost, its familiar, is still alive. It could revive at any moment. The allied armies need to get back into fighting shape, and fast. Naofumi makes the risky move of heading onto the Tortoise’s back with only a small group, and tries to find its true weak spot.

Naofumi is met by L’Arc, Glass, and Therese. They’re after the person who broke the Spirit Tortoise’s seal and is controlling it. L’Arc proposes teaming up again…

Fitoria appears when the Spirit Tortoise revives, and with her help, Naofumi attempts to destroy its heart and cut off its head at the same time. L’Arc arrives as well, but all of them are helpless before Kyo’s overwhelming power.

Naofumi wakes up in a strange prison to find him and his party at level 1, and Filo missing. They start to raise their levels in order to escape, but things quickly turn against them when a dangerous monster suddenly appears…

Naofumis party is teleported to Sikul, where Kizuna introduces the Vassal Weapon Hero, Ethnobalt. He soys he can use a piece of Raphtalia's hair and Naofumis blood as a catalyst that can create a shikigami to find her. He creates the shikigami, and they find.

Raphtalia is imprisoned in a Raybul Kingdom prison. She’s wary of L’Arc’s team, who is also imprisoned there, but asks them for help in escaping. Glass is weakened by the draining power of the prison. Raphtalia has a plan to escape, but…

Naofumi's party is overjoyed to be reunited with Raphtalia. Kizuna criticizes Glass for invading another world. Glass and L'Arc swear they won't fight Naofumi anymore, and instead find another way to solve their problem. Meanwhile, Kyo's plot proceeds.

The Wave appears before its scheduled time. Kizuna's group is teleported to it while Naofumi and his party head for Kyo's lab on Ethnobalt's ship. There, they see the true depths of Kyo's wickedness...

Raphtalia recalls having to buy clothing for her smaller self. Kizuna remembers being alone for so long. Rishia remembers Ost trying to give advice.