The goal of this study is to develop a device which is used to both energy storage and wireless power transfer for ultra-low energy applications. It is a flywheel-like device with new concepts. This device consists of a rotating module and magnetic energy harvesting module. The rotating module is a rotating mechanical device that is used to store not only rotating energy but also magnetic energy. To make it simple and low costs, we use a geared-shape magnetic material between two antiparallel magnets. The magnetic energy harvesting module is an “on demand” power receiver device that is used to convert magnetic energy to electric energy. This paper focuses on this wireless power transmission performance. We consider the magnetic core shape for the magnetic energy harvesting module, and evaluate the harvesting power and its efficiency as a function of distance between two modules.