The "Happy Set" sold at each McDonald's store comes with an original "Demon Slayer" sticker. Limited quantity. Released on March 5th.
Comes with a sticker set and an extra toy. It's random, so I don't know which one you will get. Also, the bonus toys are not "Demon Slayer". There are 5 types in the lineup.
(C) Koyoharu Gotouge / Shueisha / Aniplex / ufotable