Methods and systems for creating and rendering skins are described. The transmission assembly further includes a mechanical transmission coupled to the hydrostatic transmission and having a first range and a second range and an output shaft driven at a travel speed ratio. Since the light-emitting device is made without using any organic solvent, it is highly safe, does not deteriorate in emission characteristics, and requires only a decreased number of constituent materials. The orally-administered agent according to the present invention can be swallowed with ease and can release a medicine at intended parts of a living body. Specifically, it is possible to use a light source which gives a light stimulus to the subject’s eye, such as an LED light source, an electric bulb, a strobe, or the like, as the stimulus applying unit.