Originated in Japan, this non-registered, small size cultivar is of unidentified parentage but has
H. clavata in its background.
The green foliage is narrow, slightly shiny on top and
whitish shiny on the bottom. It produces purple flowers
from late August into September.
Mikiko Lockwood in an article on The Hosta Library titled,
A Little About Japanese Hosta Terms defines the term nagaba as narrow long leaf(ed).