Oshiko shrine has a huge stonework called 'The stone heirloom' as an object of worship.
It's called floating stone as well because it looks like float on water, like Laputa from the movie 'Castle in the Sky'.
No one knows who, why, how did make it.
And, this is the my final cache which is installed by Team Zerosen.
With sincere gratitude to all geocachers.