"When is the moment you want to forget the most?" Park Soo-ah, a geek high school girl, and Shin Ha-yeon, a grumpy tsundere, and A, a high school student, are members of the science club. Those who gathered to prepare for the school summer festival lost their minds in the heat of summer vacation Park Soo-ah, tired of the lame entry, declares the invention of the time machine...? Manipulate the past, make the future! "Leaf in Bootstrap", here we go!