Oh! It's the remote controlled robot trope... I think. That's fun, though like others I'm a bit surprised at the fantastical nature of it.
On another note, really enjoyed the translation quirk of Kitano referring to Eru as "she" in this chapter (don't remember if she got an opportunity to do so in earlier chapters). When manga have characters like this, with quite unclear genders[1], then most translators default to having them be called by a single pronoun by all characters. That pronoun might be "they" to be neutral and/or ambiguous, or whatever pronoun they were assigned at birth[2], or even rarely the gendered pronoun they weren't. But here Eru is referred to as "he" by Kagari and their mom, and "she" by Kitano and the kids last chapter. While the kids would just go by what they're seeing, Kitano's choice of words come off as recognition... of Eru as a rival. It would be weird after all if Kitano was anxious about Kagari's heterosexuality, that he'd leave her for a "realer" girl, and also called other percieved romantic rivals by masculine pronouns.
[1]As arguably is the case with Eru, who both picked up the role of a signboard girl and self-identified as a boy last chapter. Kitano is pretty clear cut though lol.
[2]Construed as being. Fictional characters are not really born per-se.