Unfortunately, these things get used for something besides harvesting rice from time to time. They are pretty ubiquitous. All of my junior high and high school students had one when I taught there. They were for maintaining the school grounds. I was a little worried I'd said something wrong the first time I walked in to teach a class and everyone had on on their desk.
http://newsonjapan.com/html/newsdesk/article/106166.php