  We argue that in ($p+3$)d string theory the existence of NS-NS type $p$-brane
with negative tension is essential to obtain background geometry $R_2$ or $R_2
/ Z_n$ on the transverse dimensions, and the usual codimension-2 brane
solutions with these background geometries already contain the negative tension
NS-brane implicity in their ansatz. Such an argument leads us, in the context
of brane world scenarios, to a conjecture that true background $p$-brane
immanent in our spacetime may perhaps be NS-NS type brane, rather than D-brane.
