Lilium formosanum Wallace

Family: Liliaceae
English: Formosa Lily
Japanese: タカサゴユリ (高砂百合) [Takasago Yuri]

This is an invasive species from Taiwan. It looks very similar to the true 'Easter Lily' but is distinguishable by the plethora of thin leaves and belated blooming period. There's also a hybrid, L.x formolongo, (シンテッポウユリ). In fact, I may have mixed up some of my photos here of L. formosanum and L. x formolongo. Anyways, like the Easter Lily, it is bred for big beautiful blooms, and it has been planted and replanted and encouraged to grow around the coastal plains here and much of Japan.

References:
Invasive Species of Japan: Formosa Lily. National Research and Development Agency, National Institute for Environmental Studies. Referenced on October 27, 2016 from https://www.nies.go.jp/biodiversity/invasive/DB/detail/81040e.html .
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）
シンテッポウユリ Lilium x formologi. Japan Ministry of the Environment. Referenced on October 27, 2016 from https://www.env.go.jp/nature/intro/1outline/list/files/149.pdf