  With a design luminosity of 50 ab$^{-1}$ and detectors with tracking
capabilities extending beyond 1 m, the Belle II experiment is the perfect
laboratory for the search of particles that couple weakly to the Standard Model
and have a characteristic decay length of a few centimetres and more. We show
that for models of dark photons and other light vector bosons, Belle II will be
successful in probing regions of parameter space which are as of now unexplored
by any experiment. In addition, for models where the vector boson couples
sub-dominantly to the electron and quarks as compared to muons, e.g. in the
$L_\mu-L_\tau$ model, Belle II will probe regions of mass and couplings
compatible with the anomalous magnetic moment of muon. We discuss these results
and derive the projected sensitivity of Belle II for a handful of other models.
Finally, even with the currently accumulated data, $\sim 200$ fb$^{-1}$, Belle
II should be able to cover regions of parameter space pertaining to the X(17)
boson postulated to solve the ATOMKI anomaly.
