We are attempting to construct multifunctional molecular assemblies focusing on the design freedom of organic molecules and their hybridization with inorganic materials. Multifunctional molecular materials are obtained by designing molecular materials from the viewpoint of conductivity, magnetism, and ferroelectricity, and by controlling their assembly states. For example, ferroelectricity can be realized by designing degrees of freedom related to kinetic dynamics in molecular crystals and by inverting dipole moments. Precise control of frequency, symmetry, and directionality of molecular dynamics makes it possible to design various properties of ferroelectric materials such as transition temperature, response speed, remanent polarization, and coercive electric field. Our research targets a variety of molecular assemblies such as single crystals, plastic crystals, liquid crystals, and gels, and we are attempting to conduct fundamental research necessary for the realization of molecular materials in the future.