Exotic neutron-rich $sd$-$pf$ nuclei and nuclear force

Recent results of large-scale shell-model calculations will be overviewed for exotic neutron-rich nuclei in the $sd$-$pf$ region. One of the most exciting findings is the change of shell structures in extreme conditions. For instance, the $N$=20 gap may be quite small in some of exotic Ne-Na-Mg isotopes leading to (near-)degeneracy of positive and negative parity states, and new magic numbers such as $N$=32, 34 may emerge in neutron rich Ca-Ti. Theoretical descriptions of these nuclei will be presented in close connection to particular properties of Nucleon-Nucleon interaction.