Under no circumstances to be confused with shirako (go ahead,
find out why), shiruko (汁粉) is a type of (very) sweet soup
made from boiled azuki beans, usually with a ball or two of
mochi floating in it.
During the Japanese winter, piping hot shiruko is frequently sold from vending machines. I discovered this the hard way one wintery and hungover day, by purchasing what my bleary eyes thought was a miniature can of Cherry Coke...