Roboppi is a maid robot that Yuusaku built and programmed himself. She works cleaning his house and is completely devoted to him—the kind of loyalty you'd expect from something designed specifically for that purpose.
There's clearly genuine affection between them, at least from Yuusaku's side. He smiles when he's around her and actually pets her, which is kind of sweet for a robot-owner relationship. But here's the thing: despite all that, Roboppi has described Yuusaku as being "a little cold-hearted." So while he obviously cares about her, there's apparently something emotionally distant about him that even his own creation has picked up on.
Content compiled by AnimeList.moe from publicly available sources.
