Wow. We all knew she was going to end up a target since she showed up in the photos but at this rate, things are gonna get violent very soon. I worry for the new girl but if she liked him that much then she shouldn't have left the chance for another girl to swoop in. Go Koharu! Take what you want!
Imagine introducing the childhood friend, who usually never stands a chance, after the MC has gotten a girlfriend. And said childhood friend is trying to turn the manga to NTR. I already hate her.
I don't like this new girl. Seriously these "alternative love interests" that always pop up in mangas only to mess with the couple dynamics are just annoying.
But you also need to more assertive senpai. Like serisouly don't let the someone else mess with your girlfriend like that.