Recent developments in the field of “elemental science” based on the efficient utilization of the intrinsic character of each element are remarkable. A variety of fascinating compounds having unusual bonding schemes and structures have been spectroscopically characterized or even isolated owing to the creative design of ligands and substituents. Representative examples include those containing silicon-silicon triple bonds, π-single bonds, five- and six-coordinate carbons, and nucleophilic borons. A notable point is that most of them are highly stimuli-responsive molecules and are thus readily converted to high-energy species that possess high potential for molecular functions. In this project, we aim to establish the fundamentals and explore applications of such “stimuli-responsive chemical species” through joint studies between leading chemists in various research fields including organic, inorganic, materials, theoretical, and biological chemistry, with the goal of creating new types of functional molecules.