  Extremal N=2 black holes in four dimensions can be described by an ensemble
of D3-branes wrapped on internal supersymmetric three-cycles of Calabi-Yau
threefolds on which type IIB superstring theory is compactified. We construct a
similar configuration, with extra RR and NS-NS three-form fluxes being turned
on. We can avoid the Freed-Witten anomaly on the D3-branes by enforcing the
pullback of these extra fluxes to the D3-branes to vanish at the classical
level. In the setup the D3-brane charge is not conserved since it is classified
as a trivial class in twisted K-theory. Consequently, the D3-branes may
disappear by encountering an instantonic D5-brane localized in time. We discuss
what happens on the black hole described by such disappearing D3-branes,
relying mainly on topological arguments. Especially, we argue that another RR
three-form flux will be left as a lump of remnant which is localized in the
uncompactified four-dimensional space-time and that it may carry the same
amount of degrees of freedom to describe a black hole, in cooperation with the
original NS-NS flux, after this transition of the D3-branes.
