What size of zori would I need if my foot is an 8 1/2 American?

Size is now noted on the product page. 
Please find the close size with yours. 

Approximate Size Conversion (JP-US):  JP US-Men's US-Women's 22.5 4.5  6 23 5 6.5 23.5 5.5 7 24 6 7.5 24.5 6.5 8 25 7 8.5 25.5 7.5 9 26 8 9.5 26.5 8.5 10 27 9 10.5 27.5 9.5 11 28 10 11.5 28.5 10.5 12 29 11 12.5 29.5 11.5 13 30 12 13.5