This such an important chapter in this story, I'm re-reading it and knowing how things play out it makes a lot of sense. A subtle difference is that Rei as a boy has a tattoo on his left cheek, it's no longer there when he becomes a girl.
Also despite Rei saying she's a Wolf we only ever see a Swan as a 'spirit animal', Betty's a Cockatoo and Arsenio's a Penguin for comparison.