There is an image of this
cultivar on the
Hosta Library. From the photo on the HL website, it appears to be a
miniature to small
size hosta with dark green leaves and narrow, creamy
white marginal variegation. It is a form of
kikutii var. polyneuron. This non-registered cultivar was
originated in the Wakayama area of Japan.
Mikiko Lockwood in an article on The Hosta Library titled,
A Little About Japanese Hosta Terms defines the term shirofukurin or shiro fukurin as white-edge(d) or
white-margin(ed) and the term yama as mountain.