The authors show that the wave functions of the non-Hermitian phase model are exactly the Grothendieck polynomials. To obtain this result, they refer to the integrable five-vertex model and introduce the skew Grothendieck polynomials for a single variable as the matrix element of the \(B\) operator. They discuss the melting crystal and derive the exact expressions of the partition function of the model. This work establishes the \(K\)-theoretic boson-fermion correspondence at the level of wave functions.