The sevenstar drink discution appear only on another story... Maybe Jumin or Seven ? She clearly treat Yoosung as a child (she nagging, not the best way to go in his route) and if it was Zen, we would already know lolol. And it can't be neither V or Ray because of the prologue; ( She is not staying at the magenta building but in Rika apartment). There are some differences with the game, the fact that she meet Rika for example. So maybe the story will also change and the route too. Like a harem or friendship end ? Who know ~
Ps ; I didn't did Jaehee route (but I will, :3) so I can't say for her. But I don't think it's the case either.