Eye's Complex

There are lots of lovers around at Christmas, but hero is alone after his third failed sex attempt with the girlfriend just a few hours ago. Everything goes fine half-way till the secret part is uncovered that is followed by manhood shrink. Sayaka calls him to drink together and advises him to wear a blindfold as a solution to his problem with seeing the crotch. Protagonist turns out to be M while Sayaka is an S, so their fun days begin. Once Sayaka brings a guest, and it changes relations between the two.

[From vndbreview]