This is a very old Japanese cultivar but still a great plant that isn't widely available or known. There is a bit of a mystery concerning it's correct name. Most sources list it as a cultivar of Acer sieboldianum but in his "Book for Maples" Masayoshi Yano lists it as Acer tenuifolium which is Acer shirasawanum var. tenuifolium. For me the leaf does seem to resemble A. shirasawanum more than A. sieboldianum so we have gone with Masayoshi Yano's name.