  In this paper we study the nonlinear Dirac (NLD) equation on noncompact
metric graphs with localized Kerr nonlinearities, in the case of Kirchhoff-type
conditions at the vertices. Precisely, we discuss existence and multiplicity of
the bound states (arising as critical points of the NLD action functional) and
we prove that, in the $L^2$-subcritical case, they converge to the bound states
of the NLS equation in the nonrelativistic limit.
