  We investigate spherical domain walls~(DWs) nucleated via quantum tunneling
in multifield inflationary models and curvature perturbations induced by the
inhomogeneous distribution of those DWs. We consider the case that the
Euclidean action $S_{E}$ of DWs changes with time during inflation so that most
of DWs nucleate when $S_{E}$ reaches the minimum value and the radii of DWs are
almost the same. When the Hubble horizon scale exceeds the DW radius after
inflation, DWs begin to annihilate and release their energy into background
radiation. Because of the random nature of the nucleation process, the
statistics of DWs is of the Poisson type and the power spectrum of curvature
perturbations has a characteristic slope ${\cal P}_{\cal R}(k)\propto k^{3}$.
The amplitude of ${\cal P}_{\cal R}(k)$ depends on the tension and abundance of
DWs at the annihilation time while the peak mode depends on the mean separation
of DWs. We also numerically obtain the energy spectra of scalar-induced
gravitational waves from predicted curvature perturbations which are expected
to be observed in multiband gravitational-wave detectors.
