The weapon was a flat-head screwdriver from a nearby shelf.

It'd been stabbed through the right side of her neck.

But Reisen wasn't dead yet.

Reisen!? What happened!?

In response, she raised her trembling hand and pointed at the exit door.

As if to say "they went that way".

I tried to open the exit door, but it was locked from the other side.

I thought that the culprit had locked it while escaping, so I tried to break it open.

But I made the wrong decision.

I've thought over and over that instead of chasing after the killer, I should've just helped Reisen right away.

Frankly, I didn't realize the wound was lethal.

It's not your fault. It's not like you're a medic or anything...

XX-sama said the same thing. Not even the greatest doctor could've saved Reisen from a damaged lower brainstem, she said.

...But it's not like these feelings are based on logic, anyway.

In any case, the door was too sturdy, so I called the custodian on my phone.

The doors in the lab are electronically controlled, so they should've been able to open it from the center upstairs.