|Release Date||August 27, 2015|
|• Chapter Chronology•|
Udaeus (黒王) is the fifteenth chapter of the Sword Oratoria manga.
In the dungeon, Ais asked Finn if she could stay behind. She added that they didn't need to leave her with anything as that might burden the others. Tione and Tiona protested her decision, however Riveria sided with Ais and asked Finn to accept her request. Finn wasn't accepting at first but changed his mind when Riveria announced that she would stay with Ais. Lefiya offered herself as a supporter to try and stay behind, causing Tona to agree with her idea. However, Tione pointed out their lack of supplies and told them that they needed to leave. Tiona had Ais promise that she would come back and the rest of the Loki Familia left.
After the others had left, the Monster Rex Udaeus appeared in front of them. Riveria remembered how the Loki Familia had killed the monster three months earlier with their whole expedition force and realized that Ais was going to try and kill it on her own. Ais asked Riveria not to interfere and activated Ariel. Using her wind, she dodged the Udaeus' attacks. She tried an attack on the ribcage protecting the magic stone but couldn't even put a scratch on it. The Udaeus fought back by using its wide area pile attack and by summoning a horde of Spartoi to assist it. Ais raised Airiel's power and managed to slice off the Udaeus' right arm.
In response to its right arm being severed, the Udaeus summoned a huge black sword from the ground and attacked Ais. Ais used her wind to escape at full speed but was still caught up in the blast. The resulting strike destroyed a massive area, dealt large damage to Ais even though she wasn't hit, wiped out all of the remaining Spartoi, and destroyed its own piles that could hit Ais through her wind. The Udaeus summoned another horde of Spartoi, ready to keep on fighting. Riveria saw this and tried to assist, causing Ais to ask her to not interefere. Riveria protested her decision but was silenced by a serious Ais.
Ais looked back at the Udaeus and knew that she could severe its left arm if she attacked it with Airiel in a direct line at fast speed. She launched herself at the Udaeus, wiping through the horde of Spartoi along the way. She blamed herself for allowing herself to be weak and try to put her desire of getting stronger as a memory. As Ais neared the Udaeus, she readied herself to strike before the Udaeus could. However, the toll of using Airiel at max power over and over struck her body and made her unable to move. She could only watch as the Udaeus went through with its attack and smashed the sword down onto her. Riveria was shocked and called out to Ais.