  We use the monodromy method to investigate the asymptotic quasinormal modes
of regular black holes based on the explicit Stokes portraits. We find that,
for regular black holes with spherical symmetry and a single shape function,
the analytical forms of the asymptotic frequency spectrum are not universal and
do not depend on the multipole number but on the presence of complex
singularities and the trajectory of asymptotic solutions along the Stokes
lines.
