  We show that a hole and a triplet spin form a bound state in a nearly
half-filled band of the one- and two-dimensional $t_1$-$t_2$-$J_1$-$J_2$
models. Numerical calculation indicates that the bound state is a spatially
small object and moves as a composite particle with spin 1 and charge $+e$ in
the spin-gapped background. Two bound states repulsively interact with each
other in a short distance and move independently as long as they keep their
distance. If a finite density of bound states behave as bosons, the system
undergoes the Bose-Einstein condensation which means a superconductivity with
charge $+e$.
