If a card says "discard a follower" as the cost, can it be a follower in play? With no other restrictions such as "from your hand" or from your discard pile", is this possible?
Discarded Followers
A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from a copy of the forum saved in October 2015, so pages it didn't save are missing. Players' names are left out; the rules officials are named. Rulings are as they stood on these dates; later rulings, the rulebooks and the Rules Archive may differ.
If a card says "discard a follower" as the cost, can it be a follower in play?
http://rules.l5r.com/Glossary_D#Discard: "As a verb "discard" means: By itself, referring to a Fate card: To remove a card from one's hand and put it in the discard pile."
No.