"I cannot imagine why." No, Yotsuyu knew why that was. "My fan serves as my wand, however." She used it as her Modification focus, too, which helped when she was drawing the necessary diagrams...

She watched carefully as Eleven performed the spell, brows arching a bit. That simple of a gesture and verbal component? Interesting.

Yotsuyu, of course, had to push the envelope. She drew her fan from her sleeve, already softly speaking the mathemagical equation and drawing the accompanying diagrams--slowly, so Eleven could at least see them. She planned to go over the mathematics again carefully before allowing him to cast it.

Then she imitated his action, sweeping her arm into the air. "Ward!"

The ward did shimmer into the air briefly before dissipating, but Yotsuyu did not seem displeased. "I had only intended for it to last for seconds, so the mathematics was me giving it a finite duration." Mostly because she hadn't been sure the actual warding spell would work. Clearly she's pleased to see it has!