This is a sport of H. longissima var. longifolia from Japan. It is a small size, green hosta with very narrow, white marginal variegation. Pale lavender flowers with 4 or 5 blossoms per scape bloom in September.

Mikiko Lockwood in an article on The Hosta Library titled, A Little About Japanese Hosta Terms defines the term hosoba as narrow leaf and the term mizu as water, 'Mizu Gibōshi' or H. longissima and the term shirofukurin or shiro fukurin as white-edge(d) or white-margin(ed).