  The discovery of a new charged structure in the $K^+$ recoil-mass spectrum
near the $D^-_s D^{*0}/D^{*-}_sD^0$ threshold, dubbed $Z_{cs}(3985)^-$,
reinforce the idea that the structure of hadrons goes beyond the naive $qqq$
and the $q\bar q$ structures.
  The existence of this state, with quark content $c\bar c s\bar u$, can be
expected from the well-established $Z_c(3900)^\pm$ and $Z_c(4020)$ states using
SU(3) flavor symmetry. The $Z_c$ structures have been explained using the
chiral constituent quark model in a coupled-channels calculation and, in this
work, we undertake the study of the $Z_{cs}(3985)^-$ using the same model.
  We are able to reproduce the $K^+$ recoil-mass spectrum without any fine
tuning of the model parameters. The study of the analytical structure of the
S-matrix allows us to conclude that the structure is due to the presence of one
virtual pole. A second state, the SU(3) flavor partner of the $Z_c(4020)$ is
predicted at $\sim\!\! 4110$ MeV/$c^2$. New states in the hidden bottom strange
sector are also predicted.
