  In this write-up, I summarize the analyses on the low-lying scalar mesons I
have done recently with my collaborators. I first briefly review the previous
analyses on the hadronic processes related to the scalar mesons, which shows
that the scalar nonet takes dominantly the $qq\bar{q}\bar{q}$ structure. Next,
I summarize our analysis on the radiative decays involving the scalar mesons,
which indicates that it is difficult to distinguish $qq\bar{q}\bar{q}$ picture
and $q\bar{q}$ picture just from radiative decays. Finally, I summarize our
recent analysis on the $\pi$-$\pi$ scattering in the large $N_c$ QCD, which
indicates that the $\sigma$ meson is likely the $qq\bar{q}\bar{q}$ state.
