The first part of the dungeon features a long hallway leading to its deeper levels. There are also the remains of an old Oresoren village, where a "Long Long Demon" forced the Oresoren out of their home. Past the village is an old railway system that penetrates the passageway. The rest of the passage leads outside to a mountain pathway.
Senel Coolidge, Will Raynard, Chloe Valens, and Norma Beatty head toward the entrance and find the mysterious youth and Shirley Fennes as they venture into the ruins. Norma suggests putting their hands on the door, and it opens up. When Chloe asks how it happened, Norma explains that Eres can be used to open doors to ruins that are normally closed tight. The rest of the group makes their way inside and leaves Norma behind while she catches up. There, Norma realizes that the passage is actually a secret passageway created during the Kingdom of Terises, which she learned about in the notes of her former teacher. As the group continues on, a huge quake occurs. Will explains that the Legacy sometimes gets earthquakes, but he never felt any this big. He then spots the pair ahead of them, and the youth initiates another fight. Norma notices how tough he is despite the group outnumbering him four-to-one. Another earthquake then occurs, and it weakens one of the nearby pillars, forcing the youth to push Shirley out of the way.
While the group checks on Shirley's condition, Norma comes to them with bad news: the recent quake blocked the entrance and they are now trapped inside. The youth bursts from the column and flies away, but as the group is about to give chase, Shirley wakens. After Shirley thanks the group for what they have done, Will advises heading forward since the way back is blocked. Senel suggests resting for a bit after seeing Shirley getting tired. Chloe and Norma start talking about the rumors they heard about the Merines, which forces Senel to stop the conversation. Will suggests putting Shirley under his protection once they return to Werites Beacon, which initiates an argument with Senel. Senel settles on leaving the Legacy, which Will agrees would be the wisest course for now. The group is then greeted by a strange little creature carrying a harp.
The critter introduces himself as Pippo of the Oresoren. He tells the group about a village nearby, though it is now empty. Will is skeptical at first, but the group eventually decides to takes Pippo's offer to lead them there. Once the group arrives at the village, they run into Pippo's brother, Quppo. He explains that Quppo is the top martial artist among the Oresoren. After looking into Senel and Chloe's eyes, he immediately recognizes them as true warriors. Norma says that she has never knew the Oresoren existed, and Will states that he has not even heard so much as a rumor despite living here for ten years. The brothers explain that they have known about them forever, and that they have been to the city numerous times. People were even handing them food just for standing there, leaving the group to suspect that the people viewed them as pets or wild animals.
As the group progresses forward, another earthquake shakes the passage and blocks the way. Quppo figures that they can get through if they dig through and asks Senel and Will to assist him. Afterward, as the group gets close to the exit, another quake occurs. The brothers explain that a Long Long Demon that lives in the passageway is what forced the Oresoren out of their old home. Will wonders if this monster is the cause of the recent quakes before the beast appears. After defeating it, the brothers bid farewell to the group, and not long afterward, Senel and Shirley quietly sneak away. Along the way, they encounter several soldiers, as well as the Terrors. Senel attempts to fight them but proves unsuccessful. Afterward, Vaclav Bolud appears, and Senel is thrown off the cliff. At the bottom of the path, Senel floats down in a golden ball and wakens, noticing that he is somehow alive. A girl, Harriet Campbell, finds Senel nearby and returns with him to Werites Beacon.