I’m reading a lot about this topic since a couple of mounths, so I want to try to explain my theory about it (even if english, is not my first language and this kind of things are really specific, so please forgive my mistakes).
First of all, I’m pretty sure that Tooru has a terrible mental illness call Dissociative identity disorder or multiple personality disorder (MPD). What is this? Long story short, there are at least two distinct and relatively enduring identities or dissociated personality states, inside the same person. The number of identities varies widely, but in my opinion inside Tooru we have only two different ones: Female Tooru and Male Tooru, that alternate their existence inside him/her. We have a strong personality (Fem) and a submissive (Male) one.
A DID symptoms is, for example, the presence of two or more distinct personality states match with the inability to recall personal information (expecially by the submissive personality, who is totaly cut off his own mind), beyond what is expected through normal forgetfulness. This could explain why he doesnt remember when she killed his all family or when he killed all during the academy period. This particular for of lack of memory is call dissociative amnesia.
These states alternately show in a person’s behavior are draw it VERY WELL by Ishida, in my opinion. Think when she approchs herself to Aura in order to obtain his help. Or when she approchs Kaneki in chapter 122. Otherwise, in the firsts chapters, the way he walk and be in touch with the rest of the team. He was goffy, shy, more masculine than the lasts chapters where her moving changes. (In particular in THAT scene with fake Haise. That was a seductress woman) (Damn it’s really hard to explain with all those he/she in contrast. Sorry.)
People diagnosed with DID often report that they have experienced severe physical and sexual abuse, especially during early to mid-childhood, and as we know, she/he was abuse and rape by his father till the day she ripped him in pieces. And then she forgot the fact. As well as she/he forgot about killing all those cats during the academy. It’s really sad as a mental desorder, because starts as an escape from a cruel reality. In this new arc, Female Tooru win over Male Tooru. The causes are many: she felt alone, adbandoned by the only one man that she ever love or at least that shows a gentle behavior. Haise’s really love him, in a familiar way maybe not a romantic one (even if I’m pretty sure that this poor soul will never have a real romantic sentiment for noboby in the future). She changes a lot of team after QS, so she has a lack of stabily, that in QS before the Rose Case was the first family he ever had. Torso probably has raped her again, throw this poor baby into the nightmare again.
And she just can’t stand on it anymore, even if she hate to be a woman. She hate to be weak again and she really want to be a man and have Haise’s love bacause she never fell this way with anyone before.
For what concerns Urie, I think that he is an hetero guy who has a big crush on Mutsuki from the moment he realise that he is a woman. I can’t blame Kuki neither, is brain elaborate that information because of his infatuation. He always try to save Mutsuki, he his really
attached to this companion, no matter if is a she or a he. Whatever, that is really sad because Mutsuki will never be what he need..
In the end, the result for me is that if you call Tooru a girl is not a big deal. Because in this moment, she probably is back to that part of life, the darkest one, when she was a woman. A really lonely little girl who deserves better. I cant blame this child, who only need help.
My point is that she doesnt feel like a guy in her BODY, but is a MENTAL state. She want to change her past, not what she is. I refer to her more than a fluid than a trans. BUT OBVIOUSLY IT’S JUST MY OPINION! I dont want to change your mind or make you understand that this is how things really goes. It’s just an intuition.
I feel so bad for her. Or for him that maybe will be never come back, like the best part of Tooru, the one he built himself was too weak for this world.
The only thing I hope is to see HIM happy again, as he was in the past.
So, this is my analysis. Feel free to tell me what do you think about! And sorry for all the mistakes I probably made, its like four and half in the morning but I really want to give my contribution ti this discussion! So please be nice and I’ll responde to all your observations!