Is Touken canon?
in my heart, yes~
but nah, personally I won’t call it ‘canon’ until Kaneki explicitly reciprocates. The way I see it, that was the whole point of this scene:
Kaneki realises that this conversation was Touka confessing her feelings but before he can form any sort of response, Tsukiyama interrupts.
And honestly, I’m glad for it. I don’t think Kaneki is ready to confront those feelings. Even with the crippling fear of one day disappearing, romance was something Haise was able to entertain; he had the time and inclination for love-filled fantasies. Much like Kaneki in the beginning of the story with Rize. But especially after Aogiri Arc, Kaneki has always been struggling under the weight of all the shit life has thrown at him and desperately throwing up walls between himself and others. Romantic feelings just don’t seem like something he’s been in the right head space to recognise or accept when he’s ‘empty inside’ as Seidou put it, both in TG and :Re. I mean, he couldn’t even understand how much the people around him loved him and wanted him to ‘live’.
I actually think this was the 1st time Kaneki had remembered and reflected on his behaviour towards Touka as Haise.
After getting his memories back, Kaneki was in a very dark place for those 6 months or so as Black Reaper so its not surprising.
It’s clear as day that Touka and Kaneki are so important to each other but I don’t think Kaneki has ever actually entertained the possibility of him and Touka together since Haise.
“Touka… and me?”
But Touka being open and honest about her feelings, spelling it out for Kaneki because he’s… a ‘bit’ oblivious to the feelings of others, was a first step. He’s always been so focused on pushing Touka away to protect her that Touka’s confession came at a huge surprise. Now (pretending that everything with Mutsuki is going to turn out A-OK) Kaneki has the time to sit them aside and examine his feelings for Touka properly, reflect on the feelings he had as Haise and figure out whether those are something he still wants to pursue. He can come to terms with them at his own pace.
I’ll just put it this way: I also thought Touka’s feelings for Kaneki was blindingly obvious but I would never have said ‘canon’ until last chapter. I also think Tsukiyama has romantic feelings for Kaneki but although they’re implied in canon, I won’t give it that label until Shuu explicitly calls it ‘love’. I follow the same rules with anything. Haise felt romantic interest towards Touka; the chapter they met again was called ‘Inherited Feelings’. That’s up to your own interpretation to decide whether that implies more about Kaneki’s side of things. Only when Ishida addresses it again will we know whether we were meant to be reading between the lines there or not.