Alternate Universe in Chaldea, where Servants are chibi-sized cats.

Taking care of cats can be a little difficult, but imagine working as a caretaker for the most arrogant, heroic spirit as a cat. The three kitties have their own unique personality, but they do share a common trait: jealousy. So make sure to wash your hands after petting the other kitties that loiter around the cafeteria!

(Creator apologizes if this doesn't make any sense.)