Actually there are 2 parts already, the 1st one with the violet haired girl, and blue-haired professor. And then there's the sequel which this screencap comes from But likewise, I too wish that the series would have gone for an extra instalment ^_^;
I would've loved to have a third installment in this series. This is one of my favorites and I wish there were more hentais like this (What is the plural for hentai? Lol)
that it is Schuym, remember if you like it do buy it, i own a copy and i must say its worth the buy, if you go to any anime cons you can find it for like 5 to 10 USD at lest the one i got it form ran me 10 at the time.