  The feasibility of shell-model calculations is radically extended by the
Quantum Monte Carlo Diagonalization method with various essential improvements.
The major improvements are made in the sampling for the generation of
shell-model basis vectors, and in the restoration of symmetries such as angular
momentum and isospin. Consequently the level structure of low-lying states can
be studied with realistic interactions. After testing this method on $^{24}$Mg,
we present first results for energy levels and $E2$ properties of $^{64}$Ge,
indicating its large and $\gamma$-soft deformation.
