Hydrangea hirta Sieb.

Picture 1 in Japan, Honshu, Kyoto, May 2008 (cultivated)
Picture 2 in Japan, Honshu, Nikko, June 2010 (cultivated) (var.albiflora Okuyama)
Picture 3 in Japan, Honshu, road to Nikko, June 2010

Description in Flora 11(2): 757 (1828)