  This paper describes a novel algorithm for tagging jets originating from the
hadronisation of strange quarks (strange-tagging) with the future International
Large Detector (ILD) at the International Linear Collider (ILC). It also
presents the first application of such a strange-tagger to a Higgs to strange
($h \rightarrow s\bar{s}$) analysis with the $P(e^-,e^+) = (-80\%,+30\%)$
polarisation scenario, corresponding to 900 fb$^{-1}$ of the initial proposed
2000 fb$^{-1}$ of data which will be collected by ILD during its first 10 years
of data taking at $\sqrt{s} = 250$ GeV. Upper limits on the Standard Model
Higgs-strange coupling strength modifier, $\kappa_s$, are derived at the 95%
confidence level to be 7.14. The paper includes as well a preliminary study of
a Ring Imaging Cherenkov (RICH) system capable of discriminating between kaons
and pions at high momenta (up to 25 GeV), and thus enhancing strange-tagging
performance at future Higgs factory detectors.
