If i remove card from my hand (face-down) it leaves game face down or face up? In other words, do my opponent have to know what i'm removing?
Removing card from game
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 i remove card from my hand (face-down) it leaves game face down or face up? In other words, do my opponent have to know what i'm removing?
Face-up.
See, Areas of the Game, Outside the Game: "Cards removed from the game become face-up when they enter this area."