Why was Mai at his house at 5:05 before and was at his house at 5:00 after he time travel? Also it seems like Robot-chan raised her death flag this chapter.
A device used by students at party to reverse 5 min back in the past in the 22th century. I guess there's a shortage of condom in that time. With how they give them by the dozen to the school rejected students, I wouldn't be surprised.