After looking over what everyone said we felt we had three strong contenders for finding the gris-gris bag and doing something with it. We decided to use the magic of random number generator to choose. Random number generator did not choose Seishirou. However, he is welcome (as is anyone) to go out looking for things once he hears they are around or to replot with us later. But for this initial few days we'd prefer he didn't stumble across any of their hidden goodies.
For a little more info in case it comes up later, the sigils are invisible to the naked eye and will probably be slightly delayed after everything else. The devil's traps will be concealed for the most part. You might find one or two on a high ceiling. Supernatural demons and angels can't sense those, so it would be rare for them to be sensed if not activated. (Though we would certainly want to work with someone's canon instead of just saying it doesn't happen in theirs!)