The Nanakusa (or, as is more usual, Nanagusa) festival is celebrated (or, more properly, marked) throughout Japan (on 7 January) these days, though, it being a not-particularly-important festival, not by everyone every year.
The festival involves eating a dish made with 7 (i.e., nana) herbs or grasses (i.e., kusa or gusa).
A similar festival is held in the autumn; similar festivals also occur in China, Vietnam, and other countries heavily influenced by Chinese culture.