Thanks for the translation
I always feel physically sick reading this series it's more than a little painful. I think some people are being just a little too hard on Nana like yeah she is clingy obsessive and controlling none of that is wrong but I don't think that means she deserved for someone already in a relationship to lead her in with the intent to sleep with her.
Nana obviously isn't free of blame here, she didn't confirm they had broken up and absolutely is obsessive and controlling, and she clearly ignores red flags that benefit her like the two toothbrushes, but that's also obvious to anyone interacting with her so it's hard not to read this as Tsukasa taking advantage of those traits. "You're so perfect, you're beautiful" "dating? No I'm not worthy of you, I just thought you could save on a hotel by coming here and I have a girlfriend"
I really do read this as Tsukasa taking advantage of Nana's negative traits to manipulate her, Nana isn't a perfect victim but she's a victim.