Letters to Our Robot Son

Arto has a problem. For one, he's a robot. He's awoken with no memory of who he is, with nothing but a mysterious letter, in a world bereft of those fleshy, talky things that made him. So why is he alone, and where have all the people gone? He stumbles upon a lost, cheeky kitten and selects it as his best friend for the adventure of a lifetime, trying to make sense of all this existence stuff. Just as Arto begins to fear he's the only sentient thing left on the whole planet, a cantankerous robot falls from the sky. She says she's his sister. And that's the problem, because she might be the reason there are no more people.