  We present the molecular gas mass fraction ($f_\mathrm{H_2}$) and
star-formation efficiency (SFE) of local galaxies on the basis of our new
CO($J=1-0$) observations with the Nobeyama 45m radio telescope, combined with
the COLDGASS galaxy catalog, as a function of galaxy environment defined as the
local number density of galaxies measured with SDSS DR7 spectroscopic data. Our
sample covers a wide range in the stellar mass and SFR, and covers wide
environmental range over two orders of magnitude. This allows us to conduct the
first, systematic study of environmental dependence of molecular gas properties
in galaxies from the lowest- to the highest-density environments in the local
universe. We confirm that both $f_\mathrm{H_2}$ and SFE have strong positive
correlations with the SFR offset from the star-forming main sequence
($\Delta$MS), and most importantly, we find that these correlations are
universal across all environments. Our result demonstrates that star-formation
activity within individual galaxies is primarily controlled by their molecular
gas content, regardless of their global environment. Therefore, we claim that
one always needs to be careful about the $\Delta$MS distribution of the sample
when investigating the environmental effects on the H$_2$ gas content in
galaxies.
