Rakkyo is pronounced raw-kyu. We loved eating rakkyo growing up on Guam. My dad would buy some from a gas station or a canteena, along with daigo too.
There are several brands of rakkyo available at Asian stores and perhaps even your local grocer. Some soaking or pickling juices are sweeter than others, some more tart. This particular recipe used rakkyo that was in a sweeter soaking liquid. It was labeled “sugar scallions (whole) in syrup.”
I've tried cutting the scallions in half lengthwise so they soak up the pickling liquid faster; it works!
Click here for this recipe: http://www.paulaq.com/rakkyo.html