  We study NSR strings in the Nappi-Witten background, which is the Penrose
limit of a certain NS5-brane supergravity solution. We solve the theory in the
light-cone gauge, obtaining the spectrum, which is space-time supersymmetric.
In light of the LST/NS5-brane duality, this spectrum should be in
correspondence with the states of little string theory in the appropriate
limit. A semiclassical analysis verifies that the relationship between energy
and angular momentum, after a field redefinition, matches the known result for
a flat background.
