It was close to nightfall when the two were still detained within the academy's classroom without a single professor in sight when Vanessa's temper boiled up and decided to blame Yuji for her detainment because she would have been cultivating her mana and sharpening her swordsmenship but instead she had to spend the rest of her day in a stupid classroom with an overconfident brat, as she saw Yuji in her eyes.
She got up on one of the chairs in the classroom and challenged him to a duel, to her surprise Yuji accepted the duel without hesitation. The hour hit 5:20pm when the duel began with her wielding a great sword and charging directly towards him but Yuji set a sort of barrier that slowed down her attack and simply flinched her sword a little.
This tiny stunt by Yuji having flinched her great sword like it was nothing enraged her even more that she infused sword aura into her sword and went at him again with greater force and she managed to break through the barrier but exhausted most of her strength and mana, which made Yuji gain an upper hand.
Yuji later spoke and said "Arise", when suddenly skeleton knights appeared from the ground upon which they stood.