A Clean Kill in Tokyo

so far up. The first time I climbed to the top and looked down, though, I couldn’t believe how high I was, and I froze. But the other kids were watching. And right then, I knew no matter how afraid I was, no matter what might happen, I was going to jump, and some instinctive part of me shut down my awareness of everything except the simple, muscular action of running forward. I had no other perceptions, no awareness of any future beyond the taking of those brisk steps. I remember thinking it didn’t even matter if I died.
    Kawamura was standing in front of the door at one end of the car, about a meter from where I was positioned, his right hand holding one of the overhead bars. I needed to stay close now.
    The word I’d received was that this had to look natural: my specialty, and the reason my services are always in demand. Harry had obtained Kawamura’s medical records from Jikei University Hospital, which revealed he had a condition called complete heart block and owed his continuing existence to a pacemaker installed five years earlier. Turn off the pacemaker, and you turn off Kawamura.
    I twisted so my back was to the doors—a slight breach of Tokyo’s minimal train etiquette, but I didn’t want anyone who might speak English to see the kinds of prompts that were about to appear on the screen of the PDA computer I was carrying. I had downloaded a cardiac interrogation program into it, the kind a doctor uses to adjust a patient’s pacemaker. And I’d rigged it so that the PDA fed infrared commands to the control magnet. The only difference between my setup and a cardiologist’s was that mine was miniaturized and wireless. That, and I hadn’t taken the Hippocratic Oath.
    The PDA was already turned on and in sleep mode, so it powered up instantly. I glanced at the screen. It was flashing
Pacing Parameters
. I hit the enter key and the screen changed, giving me an option of
Threshold Testing
and
Sensing Testing
. I selected the former and was offered a range of parameters: rate, pulse width, amplitude. I chose rate and quickly set the pacemaker at its lowest rate limit of forty beats per minute, then returned to the previous screen and selected pulse width. The screen indicated the pacemaker was set to deliver current at durations of .48 milliseconds. I decreased the pulse width as far as it would go, then changed to amplitude. The unit was preset at 8.5 volts, and I started dropping it a half-volt at a time. When I had taken it down two full volts, the screen flashed,
You have now decreased unit amplitude by two volts. Are you sure you want to continue to decrease unit amplitude?
I entered
Yes
and continued, repeating the sequence every time I took it down two volts.
    When the train pulled into Yoyogi Station, Kawamura stepped off. Was he getting off here? That would be a problem: the unit’s infrared had limited range, and it would be a challenge to operate it and follow him closely at the same time.
Damn, just a few more seconds,
I thought, bracing to follow him out. But stopped outside the doors—he was only allowing the people behind him to leave the train. When the Yoyogi passengers had exited, Kawamura got back on, followed closely by several people who’d been waiting on the platform. The doors closed and we moved off again.
    At two volts, the screen warned me that I was nearing minimum output values and it would be dangerous to further decrease output. I overrode the warning and took the unit down another half volt, glancing up at Kawamura as I did so. He hadn’t changed his position.
    When I reached a single volt and tried to go further, the screen flashed,
Your command will set the unit at minimum output values. Are you certain that you wish to enter this command?
I entered
Yes
. It prompted me one more time anyway:
You have programmed the unit to minimum output values. Please confirm
. Again I entered
Yes
. There was a one second delay, then the screen started flashing bold-faced letters: Unacceptable output values. Unacceptable output values .
    I closed the cover, but left the PDA on. It would reset automatically. There was always the chance the sequence hadn’t worked the first time around, and I wanted to be able to try again if I had to.
    There wasn’t any need. As the train pulled into Shinjuku Station and jerked to a stop, Kawamura stumbled against the woman next to him. The doors opened. The other passengers flowed out, but Kawamura remained, his right hand gripping one of the