  Yoichiro Nambu put a great foot print in nuclear physics in the era of its
fundamental developments including his pioneering insight into essential
ingredients of repulsive core of nuclear force and its relation to the
saturation of nuclear matter. The present review article focuses onto recent
developments of the interaction models between colliding nuclei in terms of
Brueckner's G-matrix theory staring from realistic nuclear forces and the
saturation property of symmetric nuclear matter as well as neutron-star matter.
A recently proposed unique scenario of extracting the saturation property of
nuclear matter and stiffness of neutron stars through the analysis of
nucleus-nucleus elastic scattering in laboratories is presented in some detail.
