Space Inflatable Membrane structures Pioneering Long-term Experiments (SIMPLE) unit is one of ISS Japanese Experimental Module (JEM) Kibo's exposed facility payloads scheduled to be launched in 2012. Manufacturing and function testing phase of the engineering model (EM) has been completed and the proto-flight model (PFM) is now underway. The SIMPLE mission consists of three experimental verifications using Inflatable Extension Mast (IEM), Inflatable Space Terrarium (IST) and Inflatable Material Experimental Panel (IMP). The combination of the experiments is aimed to demonstrate the usefulness and viability of the inflatable structures and to acquire the basic operational data of the systems. The brief descriptions of each component of the SIMPLE experiments are presented and the idea of the verification project is summarized.