  We construct a new off-shell twisted hypermultiplet with a scalar and an
anti-self-dual tensor superfields. Using the N=2 twisted superspace formalism,
we construct a Donaldson-Witten theory coupled to the hypermultiplet. We show
that this action possesses the Vafa-Witten type N=4 twisted supersymmetry at
the on-shell level. We also reconstruct the action using a N=4 twisted
superconnection formalism.
