Tree Peony 'Yoshino Gawa' (or 'Yoshinogawa')? Just a guess.

Second guess would be 'Yachiyotsubaki' (or 'Yachiyo Tsubaki'). But the leaves of 'Yachiyotsubaki' should have some sign of reddish bronze look.

Here is a link that might be useful: A photo search of 'Yoshino Gawa' from Flickr

Thank you blueeskimo. I thought it might be Yoshinogawa, but is the color too dark for Yoshinogawa? I saw the picture a few years ago and have been wanting to get one.

Have you considered Hana Kisoi?

Here is a link that might be useful: hana kisoi

I think it is Hana Kisoi

Not Hana Kisoi. The one pictured has a different petal structure than Hana Kisoi. Unless the plant is newly planted the flower structure after the plant has been in place for a number of years is fairly accurate thing to judge when trying to decide what the plant is. The original plant appears to have been in place for some time and it has a less petals and is not as symetical as Hana Kisoi.

Whatever it is, it is fascinating. Wish I have one. Changsong