"... Even if I didn't, there's no real choice to be made. Shinjiku is our home. And... I can't just give it up. I know you could pick someone else, but..." Someone better suited to diplomacy, or for healing. He's just a weapon and he knows it.

But he has to try.

"I promised I'd protect the city. I made a contract." Even if he doesn't remember doing it. Even if he was likely doing it so he wouldn't die. "I'm not turning my back on that." Sure, he could live as a human... but he doesn't know how. Not really. He pretends he does, but all he knows how to do is to hurt people.