Based on the fanfic from the link:
https://forums.spacebattles.com/threads/keys-to-the-contract-madoka-x-kingdom-hearts.716512/
" That which is caged yearns to be free. That which is broken yearns to be whole. For all things, there is a key. After one such key comes to Madoka, it sets her on the path to discovering the truth.
It's been two years since the devil split the goddess. In that time, Madoka Kaname has been living a normal life with her friends. However, she has been constantly plagued by the feeling that something is, missing, that something is wrong. She begins to have strange dreams and encounters even stranger creatures, sending both her and Homura on a massive journey across worlds they had never even thought possible. "