By page ten, the sentences grew personal. "Kenji-san wa mainichi nani o shite imasu ka?" (What is Kenji doing every day?) He hadn't entered his name anywhere. He typed: Benkyou shite imasu (I am studying). The PDF responded: "Hontou desu ka?" (Really?) The text changed color—from black to a deep red.

He sat in the dark. His phone buzzed. Mika: "Did you open the PDF? LOL don't worry, it's just a prank. My cousin made it. But seriously, delete it before it learns your full name."

He tried to close the file. The close button didn't work. He tried to force-quit the browser. The screen flickered, and the PDF expanded to fullscreen.

His throat tightened.

Kenji deleted his browser cache, reformatted his tablet, and spent the next three weeks studying from a paper textbook.

Kenji had a problem. His JLPT N4 exam was in six weeks, and his grammar was still leaking like a paper cup. His friend Mika sent him a message: "Try this. Search for 'manabou nihongo pdf'."

Page twenty. The exercises became commands. "Kenji, kuruma o mite. Soko ni dare ga imasu ka?" (Kenji, look at the car. Who is there?) He glanced out his window. No car. Just an empty street. When he looked back, the PDF had added a new line: "Mada minai de. Yokatta." (Don't look yet. That's good.)

He passed the N4. But sometimes, late at night, when he types "manabou nihongo" by accident, his autocorrect suggests: — "learns you."

He always deletes it.

He didn't click. Instead, he whispered to his laptop: "Owari ni shiyou." (Let's end this.)

Below it, a download button appeared. Not for the PDF. For something else. The label said: "Kenji_no_kioku.pdf" — Kenji's memory.