  It is experimentally observed that ratios of branching fractions for
semitauonic and semileptonic $B$ decays, known as the $R(D^{(*)})$, are higher
than Standard Model (SM) predictions. The $B \to \bar{D}^{(*)} \tau^{+}
\nu_{\tau}$ decays, except for the branching fractions, offer also other
observables, in particular, angular observables may determine spin structure of
a potential New Physics (NP) providing some clues to explain the $R(D^{(*)})$
puzzle. In this review, polarization measurements in $B \to \bar{D}^{*}
\tau^{+} \nu_{\tau}$ decays at Belle are presented and prospects for
measurements of characteristics of semitauonic $B$ decays at Belle/Belle II are
described.
