Purchased at Shimamura. Likely size 25-26cm. Quoting from the internet: These are sandals from Nishibe Chemical, manufactured until 2011. They seem to be a hybrid of the Calypso type (thong type) and the Ben-Hur type (where the thong is large and the strap separates the big toe from the other toes), so I'm guessing they're called "Kariben" (a portmanteau of Calypso and Ben-Hur).