The leather used for these slippers are normal leather. (It is not a vegetable tanning leather. Chrome-tanned sheepskin leather.)
The insoles of these slippers are made by "upcycling" scraps discarded during the weaving of denim. It is said that Japan's denim industry discards around 200,000 meters of denim each day, so we have put some of this denim to use in the cushioned insoles of our slippers. The texture of these insoles feels good, and is comfortable upon the soles of your feet.