​Planet formation is a natural consequence of the star formation process, and there is an incredible variety of planetary systems, which are significantly different from the Solar System. Advances in astronomical observation technology are capturing a surprising picture of the chemical composition in the regions where planetary systems are formed. Various complex organic molecules are found in protoplanetary-disk forming regions, and their abundances vary significantly among objects. This indicates that the Solar System may not have been common in terms of its initial chemistry, which invokes the discussion on the rarity of our existence.   On the other hand, the solar system exploration technology has made great progress, and we are entering an era in which the material of the primordial small body that records the material origin of the solar system is brought back to the earth. The combination of such studies with high-sensitivity observations of planet-forming regions will tell us the chemical origin of our Solar System and how common or rare it is in the universe.  However, to tackle these questions, we have to revisit fundamental astrochemical processes.  In the past decades, the astrochemical studies focused on chemistry under extremely low temperature and density conditions, where only barrierless exothermic reactions proceed efficiently. During the planetary system formation, on the other hand, the physical condition changes dynamically resulting in dynamic interactions of molecules between gas and dust(ice) surface. Investigation of such physical and chemical processes is crucial to understand the formation of complex organic molecules and the chemical variety of planet-forming regions.  Now, experimental studies on gas-phase and surface reactions become available which enable us to know reaction dynamics in detail.  This transformative research area aims at the re-establishment of “astrochemistry” by investigation of the microscopic chemical processes with the close collaboration of astronomy, planetary science, and molecular science, and aims at understanding the origin of the Solar System from the view of chemistry.