http://www.yomiuri.co.jp/newse/20030831wo21.htm

So this teacher is arrested because he's walking naked along the road. 
The article says:

"When the police arrived on the scene, Satoshi Manaka, a teacher at 
Higashino Primary School in Niiza in the prefecture, attempted to flee, 
but was apprehended by the officers after a 50-meter dash. He was 
arrested on suspicion of indecent exposure."

What's left to question about whether or not it was indecent exposure? 
The decency? Because he was certanly exposed.

John W.