If a Fusion Monster in a Graveyard is removed from play, does it return to the fusion deck, or does it stay in the removed from play pile?

I've been thinking about this for a while now, and have been unable to come up with an answer... Thanks in advance.

It would stay removed from play. Once a card is removed from the game it stays removed.

Unless you play a card that specifically can take it from the RFG/RFP pile and put it back in the fusion deck, graveyard, or field.
Just thought I would clarify more.
Thank you,
Azurai Aeon

A Fusion monster sent to the graveyard or removed from play is treated like any other monster and will stay in those areas unless stated otherwise.

If the Fusion Monster is sent back to your hand or deck by some card effect, it will ALWAYS go back to the Fusion Deck.