What materials are used?

Tabi sandals are made from TPU (thermoplastic polyurethane). 

Thermoplastic polyurethane (TPU) is a versatile material that combines the elasticity of rubber with the strength and durability of plastic. It's a type of polyurethane polymer that can be melted and molded repeatedly, making it a thermoplastic. TPU is known for its flexibility, resilience, and resistance to abrasion.