I hadn't paid attention, but this series was apparently made by a subsidiary of the same company that owns Minato Soft... which explains the familiarity of the humor and the sound effects.

Shukusei no Girlfriend 2

This entry in the series focuses on Maya, the heroine who serves as an antagonist initially in the first game.  Maya is a very straightforward girl with a strong desire to take care of those younger than her.  She is very much a warrior maiden with a strong motherly side (which she shows frequently).  She is also a tennen character, meaning the humor in her path lies mostly in her continual failure to understand exactly what is going on until it smashes her in the face... particularly when it comes to the protagonist's normal sexual desires.

Unlike Yuuri, is a misandrist, Maya is more of a tennen boke (one of those types who doesn't recognize romantic inclinations for what they are).

Shukusei no Girlfriend 3

This path focuses on Kanoko, Yuuri's best friend and the slightly yandere-ish girl you are introduced to in the first game.  Unlike the first two, which occur around the same time period (2 starts about a month or two after the point where 1 began), this one occurs a year later, after Maya and Petra have settled solidly into their new roles.  Unlike the previous two games, which forced the heroine and protagonist (Seiji) together within the first ten to twenty minutes of the game, this one takes about twice as long to reach that point, showing Seiji gradually falling for Kanoko while Kanoko comes to realize he exists (Kanoko isn't exactly a people person).

This is the longest of the three games... the first two each took up about four hours of my time, whereas this one took up about five and a half hours.  This is perhaps because of Kanoko being the most complex of the three heroines by several degrees...  There are a few serious points to this game, but even during the serious points there is a lot of ecchi, H, and comedy.  Kanoko's dere is... dangerous.  Well, all three heroines have a powerful dere (constructed by several months alone with the protagonist), but Kanoko's stands out for the fact that she is a closet pervert of a rather hard persuasion as well as a natural nympho.  Well that, and I liked the long stretch there in the middle where 

Fujiko Disc

Fujiko's path is of decent length, and it is basically an ichaicha-only path with none of the battle time you see intermittently in the other paths.  Nor does it have an actual plot.  Rather, it uses the same setup as Yuuri's path from the first game to create a live-together situation between Fujiko and the protagonist, with the result that they end up together.  

Overall for the series

This is a pretty good series of games if you want to play something heavy on ecchi, ichaicha, and Minato soft style comedy.  If you are looking for tentacle rape and aku-ochi, you will be (mostly) disappointed.