  We review the studies on the emergent phases of superconductvity and
magnetism in the $f$-electron derived heavy-fermion (HF) systems by means of
the nuclear-quadrupole-resonance (NQR) under pressure. These studies have
unraveled a rich variety of the phenomena in the ground state of HF systems. In
this article, we highlight the novel phase diagrams of magnetism and
unconventional superconductivity (SC) in CeCu$_2$Si$_2$, HF antiferromagnets
CeRhIn$_5$, and CeIn$_3$. A new light is shed on the difference and common
features on the interplay between magnetism and SC on the magnetic criticality.
