Bad idea, for example someone could make *t that stack edo hashi fragments. Its easy too to get 5k coupons, after 1-2 months you can get that easily on alt acc. After that you can trade 10 edo hashi frags from your alt with (example) normal naruto frags 10 on your main.

Its very easy to exploit trade system on a game like this. So nope, doing that would make the kill the game.