This is a non-registered sport of H. montana found in Japan by Koshi Katsuya. It is a large size hosta with green foliage that has a yellow marginal variegation. The yellow turns to green as the season progresses.

Mikiko Lockwood in an article on The Hosta Library titled, A Little About Japanese Hosta Terms defines the term oba or ooba as large leaf, 'Oba Gibōshi' or H. montana.