  We have performed high-resolution angle-resolved photoemission spectroscopy
on heavily overdoped KFe_2As_2 (transition temperature (Tc = 3 K). We observed
several renormalized bands near the Fermi level with a renormalization factor
of 2-4. While the Fermi surface (FS) around the Brillouin-zone center is
qualitatively similar to that of optimally-doped Ba_{1-x}K_xFe_2As_2 (x = 0.4;
Tc = 37 K), the FS topology around the zone corner (M point) is markedly
different: the two electron FS pockets are completely absent due to excess of
hole doping. This result indicates that the electronic states around the M
point play an important role in the high-Tc superconductivity of
Ba$_{1-x}$K$_x$Fe$_2$As$_2$ and suggests that the interband scattering via the
antiferromagnetic wave vector essentially controls the Tc value in the
overdoped region.
