Her wardrobe falls apart

The surprise of the bus showing up leads to two mistakes being made, Ibuki letting go of the straps which made Mahiru dress fall to the ground and Mahiru quickly moved her arms up and since her arms were through the bottom of her shirt, all this did was move all of her shirt over her head so fast that it also fell to the ground. Mahiru had gone from fully clothed to naked in a matter of seconds with only her shoes and socks being the only clothes she was wearing and neither of them was covering anything.

Mahiru was completely frozen. She was too embarrassed to move with the bus that was picking them up literal seconds away from seeing her.

Chiaki and Ibuki had to act otherwise Mahiru would suffer the same ordeal they went through.