This is a slow growing cultivar from Japan is related to H. kiyosumiensis although the actual parentage is unknown and was registered by Peter Ruh of Ohio in 2006 and re-registered with new data in 2018. The pointed tip, dark green foliage forms a large size mound that is 22 inches high and 40 inches wide.

Its leaves are ovate, slightly twisted, slightly wavy, flat and very shiny on top. Pale lavender flowers bloom on scapes up to 50 inches tall bloom from mid-July into August followed by viable seeds.

According to The Hostapedia by Mark Zilis (2009), "...named for Mt. Nokogiri, a mountain not far from Tokyo."

Mikiko Lockwood in an article on The Hosta Library titled, A Little About Japanese Hosta Terms defines the term yama as mountain.