Who: Szayel, whomever
What: Investigating the disturbing reiatsu from people's hearts being stolen.
Where: All over the city.
When: Evening.
Warnings: Depends on who runs into him.
Szayel really didn't give a damn about the humans; they were expendable creatures anyway, or in Suzaku's case, easily manipulated to suit his needs. But the feeling of the residual reiatsu left behind by the humans that had disappeared was putting him on edge; whatever it was that was the cause of this, he had no desire to find if he would be affected the hard way.
He strolled casually along the street, sort of half grateful for Suzaku's terrible taste in clothing, as he doubted anyone would recognize him as an Espada in this ridiculous 'Christmas' sweater he was wearing. His zanpakutō still hung from his hip, and he rested one hand on it as the other loosely held a device he had constructed himself, his thumb pressing the buttons on it and making it generate a faint beeping noise as he walked along.
Assuming the device worked as it should (and of course it would, because he made it), it would be able to pick up on where the strange reiatsu started. If he could find the origin, he could deduce what it was, and discover a way to defend himself against it, assuming he had anything to fear to begin with. If it was caused by a human being, he doubted he would have anything to worry about, but with as many shinigami here as there were, it paid to be cautious.