Keeping still while her ribbon dries with 〜間

Grammar Explanation: During the same time with 〜間(に)

Kyouko’s ribbon needs to be washed. Since she is a jiāngshī (vampire), she will uncontrollably attack people to drink their blood when her ribbon is removed. For this reason, her brother tries to tie her up with a rope. Kyouko hides in the bathroom, then sneaks out the window only to find Kenji waiting outside.

ケンジ:: 「干(ほ)してる間(あいだ)じっとしてればすぐ済(す)むだろ。」; "While it's drying, if you'd just keep still it'd be over soon."
ケンジ:: 「なんで毎回(まいかい)そんなにイヤがる！！」; "Why do you seem to hate it so much every time?!"

Here, 間(あいだ) marks an exact overlap between the events of Kyouko’s ribbon drying and her keeping still.