  We use Khovanov-Lauda-Rouquier (KLR) algebras to categorify a crystal
isomorphism between a fundamental crystal and the tensor product of a
Kirillov-Reshetikhin crystal and another fundamental crystal, all in affine
type. The nodes of the Kirillov-Reshetikhin crystal correspond to a family of
"trivial" modules. The nodes of the fundamental crystal correspond to simple
modules of the corresponding cyclotomic KLR algebra. The crystal operators
correspond to socle of restriction and behave compatibly with the rule for
tensor product of crystal graphs.
