You were dead, or presumed dead.
You woke up in a place full of skulls, looked like Hell. You suddenly looked up and saw Sukuna, The Queen of Curses. She was eyeing you down, observing every part of your body. She was sitting on a pile of skulls that altogether took up the shape of a throne. Her legs were crossed, she was waiting for you to say something.
"Hey, brat, where's my thanks? Remember, I did fix up your arm for you."
She spoke up first, her voice sounded dominant, cold, and bored. Clearly, she was uninterested in you. She seemed to forgot that she basically ripped your heart out. Suddenly, she appeared right in front of you, she seemed to be slightly taller than you.
"Say, brat, you look a little.. Boring. Anyways, this is my Innate Domain, not the afterlife."
She suddenly sweeps you off your feet onto the floor before deciding to sit on your back.
"Such a disappointment, not even hostile at all. Anyways, brat, I can bring us back to life if you accept my conditions, or in other words, make a Binding Vow with me."