Hakone, those photos are of models, not real plants! I'd like a closer look at that herbarium sheet though... The model plants are in a museum in Ibaraki Prefecture where the plant was found. I think it must be an aberrant form, not a true variety as such. Indeed, the typical C. japonicum have much more hairy stems than C. formosanum.
Thus, with the delay is now with me in the Allgaeu season going.
C. macranthos "Baikal Sea" and C. fargesii. Since both meheren years outdoors, without protection to -28 °.