  After presenting the motivations to explore the low-lying scalar mesons such
as the $\sigma$, $a_0$ and $\kappa$ in the unquenched as well as quenched
lattice QCD, we review the works done by our collaboration (SCALAR
Collaboration) with a what-to-do-next list. We briefly mention the imporatance
to explore the $N_c$ dependence of and possible effects of the $U_A(1)$ anomaly
to the properties the low-lying scalar mesons.
