A box sat on the coffee table.

It was unassuming, really. Plain black, about the size of a shoebox, with a single round button on top. Shoto Todoroki sat on the couch across from it, staring at the thing like it might bite.

He'd found it on the way back from the convenience store, half-buried in the grass beside the path. There was no note. No address. Just the button, glowing faintly in the dying light.

“Nothing. At first.”

The door slid open, and Y/n stepped inside, bookbag slung over one shoulder. Bakugou was a few paces behind her, muttering something about the assignment, a sour look on his face.

Y/n froze mid-step. Her nose scrunched.

She sneezed.

Bakugou's muttering stopped.

The box hummed faintly on the coffee table, its button still warm.