Steve wrote
Kampyo (Pickled gourd)
http://eat.epicurious.com/dictionary...sf?DEF_ID=2354

Kampyo means "dried gourd", it is used in sushi, but usually just by
being reconstitued in broth. If you follow the link the text says
nothing about pickling. However it is slighty sweet and sour, even if
no actual pickling took place.

Or it could be a kind of Japanese pickle, suno mono
http://eat.epicurious.com/dictionary...?TERM=sunomono