After the battle in Sky Town, the party is in the presence of Byak-Ko. He tells them that they are good. He wants them to bring Jeanne to him and he'll reward them greatly. The party ask why, and Byak-Ko replies that he doesn't like being questioned and the party should simply just do what they are told. The party agrees and they leave the castle. They now have access to the glider.
The party returns to the Floating Castle after Jeanne told them of her twin sister's capture by Byak-Ko. While walking around the castle, the party comes across a key which they use to open a room that contains Mileille with three guards who engages them into battle.
After their defeat, she ask who are they. They mention they are a friend of Jeanne, she ask where her sister is and the party tells her they'll take her. Before that happens, Byak-Ko appears within the room. He tells them that he knew all this time that they defeated Gen-Bu and Sei-Ryu. He used the party, and congratulates Mileille that Jeanne is finally his. The party is shock that Mileille betrayed her sister, she tells them that power is everything and doesn't care about the resistance. Byak-Ko tells the party that he will not kill the party just yet, and imprison them.