Does "Root A" follow the fact about Takatsuki and the One-Eyed Owl? In Root A, Takatsuki does seem to be fascinated by Kaneki's name, but,


   I didn't at all expect her to be the One-Eyed Owl.


I just looked her up on the Wikia and it says that 


   she is the One Eyed-Owl as well as the horror novelist.


Is this true only in the manga or is it also true in Root A?
Yes, it's shown clearly in the anime that 


   Sen Takatsuki is the One-Eyed Owl.


They started giving hints about it in first half of the episodes in Season 2.



Season 2 Episode 1


   Kaneki joins Aogiri and is welcomed by this girl named Eto
 

 Eto seems to like Kaneki
 




Season 2 Episode 2


   Later on in the next episode, Eto removes her bandages and smiles while taking Kaneki's name
 




Season 2 Episode 3


   In the next episode, we see this author Takatsuki and she smiles the same way as Eto while hearing Kaneki's name - Can safely infer that Takatsuki is actually Eto
 




Season 2 Episode 7


   The same smile pattern after hearing Kaneki's story from Hinami. Takatsuki is Eto confirmed!!
 




Season 2 Episode 11


   I think you missed this part. It was shown after the ED theme in Season 2 episode 11. It clearly shows that Takatsuki is the 2nd Owl, and the only daughter of Yoshimura (who is also called non-killing owl)