  We non-perturbatively study the fermion spectrum in the chiral symmetric
phase from the Schwinger-Dyson equation with the Feynman gauge, in which we
perform an analytic continuation of the solution on the imaginary time axis to
the real time axis with a method employing an integral equation. It is shown
that the fermion spectrum has two peaks, which correspond to the normal
quasi-fermion and the plasmino, although these peaks in the strong coupling
region are very broad, owing to multiple scatterings with gauge bosons. We find
that the thermal mass of the quasi-fermion saturates at some value of the gauge
coupling, beyond which the thermal (pole) mass satisfies $M \sim T$,
independently of the value of the gauge coupling. We also comment on the
appearance of a three-peak structure in the fermion spectrum as a
non-perturbative effect.
