You need to say yes to fantastic elements when given the option, then take Mai to see the fox lady when prompted in a later event. The route is based on Akane’s weight I believe so feeding the volleyball girls to much early may lock you out of it.
Easiest way to do it is to not feed them at all and just wait for the events to trigger.
Here’s a quick and easy guide for people to follow
Stage 1 - 2
Mon: Go to work, Running, Party with chika/ Restaurant
Tues: Uni (Twice), Running, Party with chika/ Restaurant
Wed: Go to work, Running, Party with chika/ Restaurant
Thu: Uni (Twice), Running, Party with chika/ Restaurant
Fri: Go to work, Running, Party with chika/ Restaurant
Weekend: Gym (Twice), Go running, Sauna (Since it can only be used on weekends)
Stage 3:
play the game like stage 1 - 2 but if you want to get fat Erika go to Gym once every Tues & Thu instead and go see Yui whenever it shows up and when a certain event shows up just take erika down with you
Stage 4:
WG - Play the game as Described in Stage 1-2 but fat erika will make the gym no longer available so use it to spend more time in the sauna or just wait
Diet - Go to the Gym every night and avoid all temptations and you should get to next stage with not much issues
Stage 5:
WG - play the game as normal in Stage 1 - 2
Diet - Just keep going to the gym every night
Nene - Just either tempt her with food to become a feedee or ask her to help feed the others to make her a feeder
Important note stage 5 might glitch out and show you transitioning to stage 6 if you go on the diet route and might take a few to several in game diet stage 5 to work properly, idk what causes this