Chrysochroa fulgidissima.
well known jewel beetle in Japan but it isn't easy to find. I found their wood in a park and found some of them. they are on high tree usually. I found them same tree in 2013 but they didn't come down.
25-40mm.
trees: Celtis sinensis エノキ, Zelkova serrata ケヤキ.
japanese name: タマムシ.