Naofumi follows the slave merchant to his store, where he looks for a partner to act as his sword. But all he has the money to buy is a diseased demi-human girl named Raphtalia, whom he then forces into an incredibly harsh battle.

Naofumi has obtained a whole load of abilities and skills, and his teamwork with Raphtalia is reaching perfection, too. To prepare for the incoming Wave, he upgrades their equipment and heads to the dragon hourglass to find out exactly when it will arrive. But there, he runs into Motoyasu and the other heroes once again.

The Wave is gone, but Naofumi's relief is short-lived as Motoyasu challenges him to a duel in the middle of the celebratory banquet held in Melromarc Castle. Motoyasu insists that owning a slave is unbecoming for a hero and that Naofumi free Raphtalia at once.

In the Eastern village, Naofumi meets a girl named Melty. She instantly becomes friends with Filo and then requests to accompany the party on their journey. It seems she got separated from her guards. They travel together for a while, but when they reach the capital, they find...

After refusing to hear Melty out, Naofumi switches to planning for the next Wave. When a bunch of young soldiers ask to join his party, he agrees, but on a certain condition. At the same time, he also tries to upgrade Raphtalia's class after she hits the level cap, but all he receives is harassment.

Naofumi foils the attempt to take Melty's life and fights off the royal knights, but he's then framed for abducting Melty and killing several knights, so the party is forced to go on the run. With security tightened and checkpoints everywhere, the party receives a further blow that only makes things even worse.

Due to Myne recklessly starting a forest fire, Naofumi and his party are forced to flee to a village at the base of the mountain. However, it won't be easy to break through the knights' net. Melty suggests going to a noble she knows for help, and it just so happens that Raphtalia's past is linked to his domain.

Raphtalia corners Idol with vengeance in her eyes, her bloodthirsty blade reaching for his throat. Naofumi's words bring her back to her senses momentarily, but when Idol attacks her once again...

After being unable to for so long, Naofumi finally gets to upgrade his party's classes. He then takes part in a meeting of the Four Cardinal Heroes, held under the guise of a celebratory banquet. There, he learns of the existence of a bonus stage, with increased XP earnings. Meanwhile, Raphtalia gets into a fight at the party.

Keel and other demi-human children in the village are starting to learn how to assume therianthrope form like Sadeena. Ren is now staying in the village while suffering the effects of the Curse swords, and doing his best to fit in.

Naofumi assembles a party to pursue Gaelion, who has consumed the Emperor Dragon's Core. Gaelion's transformation is profoundly sickening Filo, so Naofumi must return Gaelion to normal within the next two days.