I think Karaagetarou made an error drawing Sakuya's right hand in panel 4,
correct me if I'm wrong.

GiantCaveMushroom said:

I think Karaagetarou made an error drawing Sakuya's right hand in panel 4,
correct me if I'm wrong.

I don't see any problem. She just tried to make that peculiar salute from Attack on Titans, but screwed up and ended up pressing her left hand against the right side of her head while her right hand is behind her back.
Maybe she broke her arm a few times, but that's no error.

GiantCaveMushroom said:

I think Karaagetarou made an error drawing Sakuya's right hand in panel 4,
correct me if I'm wrong.

That is definitely her left arm, while it should be her right arm.