  Within the SM, the yet unmeasured $\tau^-\to\pi^-\eta^{(\prime)}\nu_\tau$
decays are predicted as a suppressed, isospin-violating effect with branching
ratios $\lesssim\mathcal{O}(10^{-5})$. However, they can also proceed through
other mechanisms (such as charged Higgs exchange) at comparable rates. This has
motivated several studies of the corresponding QCD predictions for these second
class current processes. In this contribution we discuss the prospects for the
discovery of these decays at Belle-II emphasizing the Mexican involvement in
this project. Our branching ratio prediction $\sim1.7\cdot10^{-5}$ (decay
channel with an $\eta$ meson) is well within the reach of Belle-II. The
branching fraction for the decay channel with an $\eta^\prime$ meson is
expected to be between one and two orders of magnitude more suppressed.
