Japanese butterbur. (Petasites japonicus). ふき、蕗。
The stems of this vegetable look large large rhubarb stems. They can become more than a meter long. Before use, they are blanched (akunuki) and peeled. Often used in simmered food, sauteed with miso, in pickles and also as tempura or candied. The taste is somewhat reminiscent of celery.
Fuki is indigenous to Japan. Von Siebold brought the plant to Europe and you can find it now as a decorative growth in forests in the Netherlands (but it is not eaten in Europe).
[Fuki. Photo Ad Blankestijn]