Ooohh, that shines a new light on this work and explains so much, thanks!
With that knowledge I now understand why the sister looked a little off to me at first, I now see that the mangaka intentionally used the face structure she normally draws for cis male character. Great oneshot! That first panel on the first page was giving me Guro vibes, but glad to find such a gem instead.
first I was like oh it’s the robot who is a trans girl but no the robot is a cis male and a great actor and it’s the assistant’s brother who a trans man