A teenager, later identified to be child of Security Head Nagai Arata, named Nagai Kotori, enters the building. They speak with receptionist Maxwell Piper amicably for about 30 minutes. Kotori hands an unidentified ID card to Maxwell, allowing Kotori full access of the building once logged. Kotori then proceeds to enter the back rooms, presumably going up the stairs.
Kotori stops at the end of the stairwell, taking a moment to stretch their legs, and heads to the women's room on the floor. They spend 10 minutes in the unsurveilled restroom before coming back out again, pacing up and down the hallway while opening and closing their fists in front of them. They then proceed to locate the door of the office of Nagai Arata, kneeling down and messing with the door handle. After 5 minutes of effort, the door is unlocked.
Kotori enters the security office, closing the door and locking it behind them, before approaching the computers. From one of their pockets they procure a USB thumbdrive, pop the cap, and jam it into the computer. They spend the next hour copying classified files onto the drive, including several maps, video files, and encryption keys. They spend about an hour doing this, using the time spent loading the files nervously pacing around the room and biting their nails. A couple times they appear to be startled by noises, but the cameras don't have audio. They continue this process for the whole hour, although their pacing pattern changes over the course of that hour. At the end, they pocket the drive and leave the way they came, re-locking the door behind them.
Kotori returns down the stairway, walking slower than when they arrived.
Maxwell sleeps at her desk, and Kotori walks past her outside without waking her.
Kotori expels the contents of their stomach on the sidewalk and collapses in the snow. A young woman with long black hair and similarly-colored attire approaches them and places a hand on their shoulder, before pulling a bottle of water out of his pocket. He offers it to Kotori, who takes it and smiles. They give the woman the thumbdrive, and the two exchange a few words, before the woman pats Kotori's shoulder and walks away. Kotori sits for a few minutes, drinking the water, before leaving in the opposite direction.
Overall, I think this incident is a very clear indication of what's going on. I will speak with Maxwell and Arata about this incident. Cameras are to be watched more carefully from here on out. This is a very dangerous leak, and the fact that it was perpetrated by a 14-year-old does not make it any less potent, given there's an accomplice... Or client. - M Aesop.