Sensei is probably my favorite character from any Okada Kazuto manga. The way she is drawn and her behavior... her presence is so overwhelming. I think it's easy to see why Daichi is willing to let her voice and image have so much control over him. She's fantastic.
What I really love about this is how subtle Sensei's sadism and Daichi's masochism are. Hell, I'm not even sure if Daichi really is a masochist at all.
It'd be really hot to see Sensei slowly reveal her inner sadism. It's definitely there underneath the surface.