I am so far studying dark matter (DM) in particle physics; proposing interesting DM candidates (from various viewpoints, e.g., new physics at TeV scale, neutrino masses/mixings, baryon asymmetry of the universe, strong CP problem, grand unification, flavor physics, thermal history of the universe including cosmic inflation and phase transition), finding new mechanisms on DM processes, suggesting experimental methods to test the candidates, and contributing to DM search projects by showing the range of DM mass and interactions, through various international and interdisciplinary collaborations with high-energy experimentalists, cosmologists, astronomers, and even chemists. Please click the above “URL” link for more details, where a few selected studies I have done are summarized.