A girl is spanked in episode 2 in "Jitsu Wa Watashi wa".
I found this episode uploaded in the link below,
http://www.dailymotion.com/video/x2xvpbe
http://www.anitube.se/video/84123/Jitsu-wa-Watashi-wa-02
and she is spanked after 17:00.
i do not know the story well,but this girl,AIZAWA Nagisa ,not real name? says she is to be spanked before people after the Court-martial if her true character;alien,robot,spy? is revealed.
And we can read similar episode,episode 86 in the manga version in comic 11.
i can not find comic 11 on amazon.com...