Haruto hears a rumor about an unbreakable sword thrust into the bottom of the sea, and heads out to sea on Captain Alwida's ship. Haruto finds his old pal Pleiades at the bottom of the sea. However, when he tries to pull it out, a huge snake monster named Aegir appears. Meanwhile, Takanori meets up with Haruto and Satsuki in the real world and tells them what he's discovered about Asahi's secret.