This image is unavailable on Donmai. Go to Danbooru or disable safe mode to view (learn more).
Artist's commentary
From what I hear, the turbine was spinning at incredible speed when it shattered into four pieces. It seems they adorned the place with it as a warning so the same accident wouldn't happen again.
Today is Touhou: Tales of Ise in Mie Prefecture's city of Ise. I look forward to meeting all the attendees.