79248cm/s said: Wait, whats up with the strangely erotic tooth brushing?
It's a parody of a scene in Nisemonogatari (in the anime, it's episode 8). Araragi Karen is voiced by Kitamura Eri (same seiyuu as Yui).
*brush brush*Dum... Dummy!I came here to tell you "Thankonomics"...Because I...If I tell you my true feelings. I'll... Disappear... As a result...*blush**grab**pant**pant*