Rio has practically nothing, just the clothes on his back and a bag of food someone gave him while he was loitering in the street.
It is thanks to Rio sitting next to a dumpster that he sees a baby in the trash that looks completely frozen.
With what little strength Rio has left, he is going to not only raise his new sister but do everything in her power so that she has what he never had. Little by little, Rio's love becomes an obsession impossible to contain.
Dealing with his shitty life is already a problem in itself, but things really get complicated when Rio discovers that despite all his efforts, his sister doesn't feel what he expected.