After you totally finish Fiona's first path (when the UI changes, etc...), start a NG+. Go to the greenhouse and start the revenge storyline there. I can't remember if it's initiated automatically or if you need to do the normal Fiona meeting stuff (helping at greenhouse, having high botany, etc) first.
Thank you.
So far I'm very satisfied with the revenge path. However, I have a question about the new impossible challenge...
I notice that some of the requirements to unlock their secret fantasy are tied to the side content of the game. My question is if is needed doing SAO or awareness group storylines to unlock the secret fantasy of ANY of the challenge's girls?
In my first playthrough I completed both the SAO & awareness group storylines, getting their respective mementos (which I don't see in the new update). After I got the Emma's ending in the affectionate tamed Abby extended ending (which I reload to do the Emi ending instead), I been avoiding any piece of content related to Riley in all my "new game +" playthroughs. So unless there's a way to fight back or get free of their "training" I don't think I will do that again that storyline. Especially when the SAO progress reset with every cycle.
Outside of that, the game is very good. I'm impressed by the quality of the writing. So far my favorite storyline is Maddison bull path. I really enjoy it.