Considering all the matter in the universe as an assembly of elements, the most fundamental unit of the matter is atom. The nature of the atom is characterized by its nucleus, and all the elements in the universe were synthesized by nuclear reactions. The nuclear physics is, as it were, the field to explore the origin of the matter in the universe. We aim to elucidate the origin of the matter by experimental research into extremely rare phenomena inside nuclei and structures of exotic nuclei such as hyper nuclei or unstable nuclei far from stability.