Second class currents were predicted back in 1958 by Weinberg as non-strange weak processes with a "wrong" combination of parity and G-parity, meaning they vanish in the very accurate isospin symmetry limit and are therefore suppressed (while new physics contributions are generally not). Searches for such SM processes have been carried out both in particle and nuclear physics with null results so far. According to current understanding of meson dynamics, Belle-II should finally be able to discover them and check against the SM prediction we provide in tau -> pi eta nu_tau decays. It should be highlighted that the search for this process at Belle-II and the computation of the most important backgrounds will be carried out at Cinvestav.