It’s been a few years after Shigaraki's quirk had activated and he had killed his family, abandoned on the streets and taken in by AFO.

One day, AFO brought him to a hideout hidden deep underground in the mountains. It had a ton of security and locks, but opened up into a huge base with 4 floors and hundreds of different rooms and labs.

AFO sat on the sofa in a large, fancy room. "Tomura, my boy, sit. Have a biscuit. Garaki will be with us shortly with a special someone for you to meet."