  We have studied modulated inflation that generates curvature perturbation
from light-field fluctuation. As discussed in previous works, even if the
fluctuation of the inflaton itself does not generate the curvature perturbation
at the horizon crossing, fluctuation of a light field may induce fluctuation
for the end-line of inflation and this may lead to generation of cosmological
perturbation ``at the end of the inflation''. Our scenario is different from
those that are based on the fluctuations of the boundary of the inflaton
trajectory, as clearly explained in this paper by using the $\delta N$
formalism. In this paper, we will consider the perturbation of the inflaton
velocity that can be induced by a light field other than the inflaton. We also
explain the crucial difference from the standard multi-field inflation model.
We show concrete examples of the modulated inflation scenario in which
non-gaussianity can be generated. We also discuss the running of the
non-gaussianity parameter.
