Polygonatum macranthum Koidz.

in Japan, Honshu, Kitakata, June 2010 (pictures 2 & 3)
in Japan, Honshu, Ainokura, June 2010 (pictures 4 & 5)
in Japan, Honshu, Road to Takayama, June 2010 (pictures 6 to 11)