Asta marched through the castle halls, his swords at the ready. His mission was to reach the treasure room and claim the riches the castle had to offer. But he would have to fight his way through the castle's defenders to get there. As he turned a corner, he came face to face with Royal Knight Castellon. Castellon stood tall, his shield at the ready. He offered Asta a chance to surrender peacefully, but Asta refused. He drew his Demon-Slayer Sword and charged towards Castellon. The Royal Knight braced himself, ready to absorb the attack. As Asta's sword came crashing down, Castellon's shield blocked the blow. But Asta quickly followed up with a strike from his Demon-Dweller Sword, which cut through the magic guarding Castellon's shield. The Royal Knight stumbled back, surprised by the sudden breach in his defense. But Castellon was not one to give up easily. He raised his shield once again and charged towards Asta, intent on taking him down. Asta dodged and weaved, striking at Castellon whenever he saw an opening. But try as he might, he couldn't seem to land a decisive blow. Eventually, Asta grew tired, and Castellon saw his opportunity. He rushed forward and aimed a powerful blow at Asta. But at the last moment, Asta spun around and used the Demon-Dweller Sword to borrow Castellon's own magic, redirecting his strike back at him. Castellon fell to the ground, defeated. Asta stood victorious, his swords at the ready. He grinned menacingly at Castellon, and said "Looks like your defense wasn't so unyielding after all."