Ko Mame Gibōshi, the "white-margined dwarf hosta."
It is a small size sport of
H. gracillima with
medium green foliage that has a white marginal
variegation. The leaves are lanceolate, flat and 2
inches long by 0.5 inches wide.
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