Fall is the season for the tubers in the taro family, but the stalks of several taro are just coming to their midsummer peak. In Japan, these taro stalks are referred to as zuiki in general, and they feature prominently on the classic summer washoku menu.
There are many categories of roots and tubers eaten in Japan today, most of whose names incorporate some variation of the word imo. There are true potatoes and sweet potatoes — jaga-imo and Sastuma-imo. Then there are wild or native-but-cultivated tubers, including true yams, called broadly yama-imo. Finally, there are the taro relatives lumped under the sato-imo appellation. The "sato" in sato-imo means "village" or "hometown" and implies a cultivated crop of nonnative origin.
Sato-imo culture predates rice cultivation in Japan, arriving from India by way of Indonesia in the late Jomon Period. Most sato-imo are raised for the waxy tubers, which are occasionally grated and eaten raw or steamed; if not, they're left whole and boiled then simmered slowly in a flavored stock. However, the stems of a few of these tubers are also eaten. A few members of the sato-imo family have, in fact, come to be cultivated just for the stalk.