  We obtain the affirmative answer to the conjecture in [15]. More precisely,
let X be the affine geometric crystal of type G^(1)_2 in [15] and
UD(X,T,\theta) a ultra-discretization of X with respect to a certain positive
structure \theta. Then we show that UD(X,T,\theta) is isomorphic to the limit
of coherent family of perfect crystals of type D^(3)_4 in [7].
