Here's a theory that perhaps is a bit out there concerning the similar faces between the different characters: Since the world does revolve around Seol-A and No-rae, every other character's purpose is to slowly drive the main characters to each other. In the case of Seol-A, the other foil characters look like No-Rae, and vice versa for No-rae (even the dudes resemble the two main characters in dude form).

Anyway, this series prompted me to join this site, and so I'll take the opportunity now to say a big THANK YOU! to the site, and all the people who work hard getting the yuri goodness on this site and to my computer. And of course, all the people working on this series!