  Flavor symmetries are useful to realize fermion flavor structures in the
standard model. In particular, discrete $A_4$ symmetry is used to realize
lepton flavor structures, and some scalars which are called flavon are
introduced to break this symmetry. In many models, flavons are assumed to be
much heavier than the electroweak scale. However, our previous work showed that
flavon mass around 100 GeV is allowed by experimental constraints in the $A_4$
symmetric model with residual $Z_3$ symmetry. In this paper, we discuss
collider search of such a light flavon $\varphi_T$. We find that an electron -
photon collision, as a considerable option at the international linear
collider, has advantages to search for the signals. At the electron - photon
collider flavons are produced as $e^-\gamma \to l^- \varphi_T$ and decay into
two charged leptons. Then we analyze signals of flavor-conserving final-state
$\tau^+ \tau^- e^-$, and flavor-violating final-states $\tau^+ \mu^- \mu^-$ and
$\mu^+ \tau^- \tau^-$ by carrying out numerical simulation. For the former
final-state, SM background can be strongly suppressed by imposing cuts on the
invariant masses of final-state leptons. For the later final-states, SM
background is extremely small, because in the SM there are no such
flavor-violating final-states. We then find that sufficient discovery
significance can be obtained, even if flavons are heavier than the lower limits
from flavor physics.
