This reminds me of Bruce Cervon's Dirty Deal trick. Five identical cards are shown, and a new card with different back design is swapped in for one of them. The backs of the five cards are now all matching the added card's back. This is repeated four more times, each time all cards taking on the new design of the newly added back!! Finally, the five cards change to five different back designs, but also to a Royal Flush on the faces.
A rare packet effect from Tricks Co in Japan, that has not been available for about 20-25 years. Came across a couple in some new-old dealer inventory, and so you have a chance to add this one to your Tricks, Co Ltd. collection.