  We consider a situation where right-handed neutrinos couple to a light scalar
which is possibly a Nambu-Goldstone boson resulting from high-energy symmetry
breaking. Its coupling is typically complex-valued and flavor-dependent. In
this work, we investigate the possibility of the leptonic asymmetry generation
in the Universe from the right-handed neutrino decay to flavorful light scalar.
Furthermore a new source of asymmetry generation from a single decay process is
pointed out, which is characteristic of the present setting.
