  A feasibility study is performed for searching vector-like leptons at a muon
collider, in the context of the "4321 model", an ultraviolet-complete model
with rich collider phenomenology together with potential to explain recent
existing some B physics measurements or anomalies. In this paper, we perform a
Monte Carlo study with various machine learning techniques, and examine the
projected sensitivity on vector-like leptons over a wide mass range at a
TeV-scale muon collider. We find that a 3 TeV muon collider with only 10/fb of
data can already be sensitive to cover the mass range of a vector-like lepton
up to 1450 GeV.
