THE most touching anime I've ever seen. I first discovered it almost a decade ago, and recently re-encountered it on YouTube. It's power comes essentially from the contrast between the lil robot's fragility, known from the beginning, and her clearly parental feeling for the male character. (Note the generic name given for these robots in the anime sub.)
The terrible fact that we and all our loved ones are going to die makes all of us humans, even the young who are the main watchers of anime, carry a hidden wellspring of sorrow at that fact of inevitable loss, whether past, of our parents, or future of our later loved ones. This wellspring in expertly tapped in this short anime. And so is the love that we all have a capacity to feel.