The last part was absolutely wonderful. Couldn't care much about the first half+, but the last part with Sensei awakening to a smell fetish was a good strike to my tastes (2D-only, of course, ahahaha). Fukukuku, what an enjoyable show... (@the end)
Riko and Ako is much cuter and 160% less disturbing/sick when they keep themselves under control, like this episode... I wish they could stay like this, but who knows when they go creepy again. The parents appearing and talking is sickening enough though...