I am working on particle astrophysics and cosmology, in particular gravitational collapse of stellar cores, supernova neutrinos and inflationary models in the early universe. Currently I am working on 1)Propagation of UHCRs (Ultra High Energy Cosmic Rays) in intergalactic space and their observational anisotropies, 2)Magnet-rotational collapse of stellar cores as the model of supernovae and the engine of gamma ray burst sources, 3)Emission of gravitational radiation and neutrinos from collapsing stellar cores, 4)Phase transition of ultra high density matter, in particular nuclear pasta structure in neutron stars and supernova cores, and so on. My research achievements include: 1)proposal of the neutrino trapping theory that neutrinos are confined and Fermi degenerate in supernova cores, 2)proposal of the accelerating expansion model in the Early Universe (Inflationary Universe Model),and solving the monopole overproduction problem by Inflation (with M.Einhorn), 3)proposal of multi-production of universes during Inflation (with M.Sasaki,H. Kodama and K. Maeda), and 4)pioneering works on astrophysical and cosmological constraints on the mass and lifetime of Weakly Interacting Particles such as neutrinos and axions (with M. Kobayashi and H. Sato).