  Kirby and Thompson introduced a length of a trisection. They also defined the
length of a 4-manifold as the minimum of length among all lengths of trisection
of a 4-manifold. In this paper, we consider trisections whose Kirby-Thompson
length is 2. Kirby and Thompson conjectured that length 2 trisection is a
trisection of 4-manifold with length 0. We shall prove this conjecture in this
paper.
