  In order to explore various aspects of stellar evolution, supernovae, gamma
ray bursts and nucleosynthesis, we have developed a new efficient stellar
evolution code. In this paper we describe this new code and compare the results
with the ones calculated by the previous code. Specifically we focus on the
progenitor evolution of lower end of the Fe-core collapse supernovae, and mass
distribution of remnant neutron stars. We describe how different assumptions
will lead different neutron star mass distribution. We also review recent works
of our research group.
