This non-registered cultivar is a sport of H. longissima from Japan. It has green foliage with a yellow marginal variegation. The plant forms a small size (6 inches high by 9 inches wide) mound with narrow foliage which has a shiny on top and bottom. Its leaves are narrowly elliptic (strap shaped), smooth textured without waves. Flowers are medium purple in color with purple anthers and are borne from mid-September to October.

Mikiko Lockwood in an article on The Hosta Library titled, A Little About Japanese Hosta Terms defines the term hosoba as narrow leaf, the term fukurin as margined or edged. and the term mizu as water, 'Mizu Gibōshi' or H. longissima.