This is one of those cases where there are two hostas with the same name. Neither is registered with The American Hosta Society. The first one to be registered would become the "official" hosta of that name and the other would have to be renamed.

Mikiko Lockwood in an article on The Hosta Library titled, A Little About Japanese Hosta Terms defines the term kinakafu or ki nakifu as yellow-center(ed).

These two cultivars were listed on the MyHostas Database website.

One cultivar is a non-registered sport of H. longipes  sparsa from Japan although it is described as the medial (center) variegated form of H. 'Tardiflora'.

According to The Hostapedia by Mark Zilis (2009), this is a sport of H. 'Tardiflora' named 'Tardiflora Kinakafu'. It is a green hosta with yellow medial (center) variegation, "but identical to 'Tardiflora' in every other way..."

Hosta Helper will call this plant 'Kinakafu Aki' (Japan 1)

Another non-registered cultivar of this name is from Japan and is a sport of H. longipes.

Hosta Helper will call this plant 'Kinakafu Aki' (Japan 2)