Now i don't want to flog a dead horse, because i am wholly on the side of "Discard does not mean the same as Remove", but cus the Kamaitachi has an ability that says (Shortened down to laziness) "...has an upgrade Discarded (or otherwise removed)...." does this lend any weight to my argument?
If they WERE the same, why would they need to add in that extra part of the ability text?