There is an image of this cultivar on the Hosta Library. From the photo on the HL website, it appears to be a small size hosta with wavy green leaves and wide white medial (center) variegation. The white takes up as much as 50% of some leaves so this is probably a slow growing plant due to the lack of chlorophyll. Also, it would have thin substance to the foliage. This non-registered cultivar was originated in Japan.

An article about H. 'Reiho' by Akira Horinaka in The Hosta Journal (2006 Vol. 37 No. 1) says,  "This is a well-known diminutive hosta. A hybrid with white-centered leaf and a deep green margin, it was the progeny of a white-veined cultivar of 'Fortunei'...and the species H. venusta...H. 'Reiho' has been a prized cultivar; it sold at 11,000 yen (about $1,000) for a single division in 1988."

An article about H. 'Reiko' by Akira Horinaka in The Hosta Journal (2006 Vol. 37 No. 1) says,  "H. 'Reiko', which has some of the most beautiful leaves I have ever seen...is a medium-sized hybrid cultivar that maintains its coloring throughout the season. It has a large leaf with white variegation. It has been one of the highest-priced hostas, rivaling 'Reiho'...It is a strong grower and keeps its beautiful leaves well into November."