[He smiles, though there's something melancholic and knowing about it. It's an extremely reasonable response, and he expects that when he tells someone. He suspects her reaction will be much worse when he eventually tells her why it happened.]

You'd like to think in most cases, someone wouldn't need to have that much of their body replaced, yeah?

[He shudders to think of what someone might have to go through if they needed that much replacement. For Hayato, that was not actually the case. His body had been fine.]

Mm. I can't tell you all the exact science behind it, that was more of my partner's specialty, but it's a mix of wind turbines and nuclear energy.