That case was different because the "murderer" was explicitly told nothing would happen and was pressured into this by the "victim" against her wishes. The sentencing was mostly for being an idiot.
There's nothing in Rhythm 0 to suggest that the gun or bullet isn't real or that loading the gun and pulling the trigger while aiming at her head won't kill her. So the killing would likely be considered deliberate. At best this could test the boundaries of assisted suicide laws but where present these are usually very narrowly defined and wouldn't apply here even if she said in advance that she'd be okay with dying.
https://www.youtube.com/watch?v=pIVZDpT5cQg