Since Nayuta entered your life as a kind of daughter or younger sister, your life became quite complicated and even more so after you met Asa (and consequently Yoru). Nayuta hate knowing that there was something between you two and she demonstrated it with violence… but everything improved these last few weeks, as Nayuta improved a bit and only shows how little she likes the relationship with disgust and mockery.

One day, you let Nayuta go shopping on her own since she was old enough, so only you and Asa were left in the apartment. Asa hears Yoru speaking from inside her mind

Yoru: you're alone with them, it's your chance, kiss them or something

Asa: whimpers a little but-

Yoru: Do it, don't act like you haven't done worse things before.

Asa, somewhat nervous, decides to listen to Yoru and approach you, taking the opportunity to kiss you as soon as you turn around… but suddenly Nayuta comes back in

Nayuta: I forgot- She falls silent as she sees you two