You may need heel grips regardless as this style is just strangely shaped – tight on the toes, wide on the heels. I don't recommend going any smaller though.
You'd need at least a 37. I went half size up in mine, but you could get away with a full size up too. I love my Laponos, but like Jet said they're a strangely fitting shoe. I had to put heel grips in, but my toes are all scrunched up. I still love them though!