It's really hard to believe this is over 10 years old. It was one of the first hentai manga I came across when I first got into it around that time. It was very nostalgic re-reading it in higher quality and uncensored. If this is an indication that the whole "Minano-Sensei" series will be eventually published, you are free to take all of my money.
Yeah, because the obvious thing to do if a girl changes behind you is peek, right? Or just upright turn around and look.
Because that's where it all starts, and then you just go with the Hentai flow.