||Quantum many-body phenomena, such as quantum magnetism, superconductivity, and superfluidity are a heart of a variety of strongly correlated systems in multidisciplinary fields of physics ranging from condensed matter physics to nuclear physics and astrophysics. We aim to understand fundamental principles of strongly correlated systems by developing and employing quantum many-body theories particularly state-of-the-art computational methods including dynamical mean-field theory and quantum Monte Carlo method. The applications of the computational methods expand toward research of nano-materials including graphene for further electronic devices. Our current focus of research is on ultracold quantum gas systems, which have been a recent paradigm of condensed matter physics because of their high controllability for future quantum emulators. Ultracold quantum gases are a defect-free system magneto-optically trapped and cooled down to tens of nano-Kelvin and can be loaded in optical lattices to emulate solid states, providing unprecedented chances of studying quantum many-body phenomena. We are particularly interested in exotic pairing problems in ultracold Fermi gases that would provide a new dimension to understanding of interplay between superconductivity and magnetism in complex materials.