Mikiko Lockwood in an article on The Hosta Library titled,
A Little About Japanese Hosta Terms defines the term
junpakuka or jyunpaku-ka as pure white flower.
cultivar name was mentioned in the Lockwood article with no further
details but we can probably expect that it is a plant with pure
white colored flowers. As a sport of the species
Hosta hypoleuca, it should be a
medium size hosta with long leaves that come to a point at the
tip. The petioles would have reddish purple dots and it would
bloom from late July into August.