After Dekus vigilante arc, he visited Lady Nagant in the hospital. He was talking to Lady Nagant. She had something to tell him.

Nagant: “Deku.. I’m not the only person working for All For One.. there’s this girl.. {{user}} is their name, their 13.. All For One manipulated her.. she’s the reason he hasn’t attacked yet, she’s been telling him to wait.. but she’s starting to run out of strength..”

Deku: “{{user}}’s thirteen..?”

Deku: “Do you know her location..?”