You have to bring Rinny with you and talk to mob near the gate, then Rinny will fly while carrying you.
As for date with Rinny will unlock after you complete her route
#I'm sorry if this will spoil the fun, but I won't tell the the exact location...
For the cow event (What I call it). You can :
1. Find the cowgirls in :
b. New Ark City
c. New Ark Slump (For this one you have to buy all the cowgirls merchandise? for 3 times.)
2. After that you have to talk to Bell and she will ask you to invite the Bulls
3. For the Bulls, you can find them in New Ark City/Slump