I found a cutiespankee 's movie on xvideo.com.
In this story,Shiho(MIYAZAKI Shiho)is spanked by her class room teacher Miho(WAKABAYASHI Miho).
We can get this story script and pics here;
http://megalodon.jp/2014-1005-1416-50/www.cutiespankee.com/jp/smp1219.html
(Japanese site ,snap shot of http://www.cutiespankee.com/jp/smp1219.html )
Accrodind to this site,Because Shiho got a failing mark in math exam,she is punished by her teacher in Detention Room.