  The small neutrino mass observed in neutrino oscillations is nicely explained
by the seesaw mechanism. Rich phenomenology is generally expected if the heavy
neutrinos are not much heavier than the electroweak scale. A model with this
feature built in has been suggested recently by Hung. The model keeps the
standard gauge group but introduces chirality-flipped partners for the
fermions. In particular, a right-handed neutrino forms a weak doublet with a
charged heavy lepton, and is thus active. We analyze the lepton flavor
structure in gauge interactions. The mixing matrices in charged currents (CC)
are generally non-unitary, and their deviation from unitarity induces flavor
changing neutral currents (FCNC). We calculate the branching ratios for the
rare decays \mu\to e\gamma and \mu\to ee\bar e due to the gauge interactions.
Although the former is generally smaller than the latter by three orders of
magnitude, parameter regions exist in which \mu\to e\gamma is reachable in the
next generation of experiments even if the current stringent bound on \mu\to
ee\bar e is taken into account. If light neutrinos dominate for \mu\to e\gamma,
the latter cannot set a meaningful bound on unitarity violation in the mixing
matrix of light leptons due to significant cancelation between CC and FCNC
contributions. Instead, the role is taken over by the decay \mu\to ee\bar e.
