  In this work, we investigate the long-time asymptotic behavior of the
Wadati-Konno-Ichikawa equation with initial data belonging to Schwartz space at
infinity by using the nonlinear steepest descent method of Deift and Zhou for
the oscillatory Riemann-Hilbert problem. Based on the initial value condition,
the original Riemann-Hilbert problem is constructed to express the solution of
the Wadati-Konno-Ichikawa equation. Through a series of deformations, the
original RH problem is transformed into a model RH problem, from which the
long-time asymptotic solution of the equation is obtained explicitly.
