Apostasia nipponica Masam.

Family: Orchidaceae
Japanese: ヤクシマラン (沖縄千鳥) [Yakushima Ran]

This small orchid, only a few centimeters across, is easily overlooked, even stepped on when it's not in bloom. It's unusual to come across a specimen large enough to have multiple flower clusters. I think it used to be considered a subspecies Apostasia wallichii.

References:
新版　屋久島の植物 川原勝征,初島住彦(監修),2001：南方新社
米倉浩司・梶田忠 (2003-)　「BG Plants 和名－学名インデックス」（YList），http://ylist.info（ 2019年8月14日）
Pfahl, J. Internet Orchid Species Photo Encyclopedia. Referenced September 4, 2016 from http://www.orchidspecies.com/apostwallichii.htm