Understanding neutron star physics is my research topic. Neutron star is provided via supernova explosion, which happens at the last moment of life of massive star. Neutron star is a unique laboratory for understanding the physics in extreme states. In fact, the density inside the neutron star significantly exceeds the nuclear standard density and the magnetic and gravitational fields around/inside the star become much stronger than those observed in our solar system. So, as an inverse problem, one could extract some aspects of physics in such extreme states via the observation of neutron star itself and/or the phenomena associated with neutron stars. For this purpose, (gravitational wave) asteroseismology is a powerful technique, which is similar to seismology in Earth and helioseismology in Sun. With this approach, we are trying to extract the "invisible" neutron star properties. Since our research is not only in astrophysics but also strongly associated with nuclear physics and condensed matter physics, I am very happy if I can make an interdisciplinary collaboration with the members of iTHEMS for solving a problem in neutron stars.