Can you please add a feature that allows us to trade unusable skillbooks for something equitable?

It seems like every time you make skillbooks available as a major reward, I can't use them. For example, I have 3 Naruto skillbooks in my inventory that I got AFTER I spent a lot of time and effort to get him 5-starred and fully broken through (as it is now, I could sell the skillbooks, and get 300 coins...but that, in no way, balances out with the 300-400 ninja frags that I used.

Most recently, you've announced for December that Sasuke's skillbooks will be released....another ninja I have 5-starred and fully broken through...so more useless skillbooks sitting in my inventory.

If selling/redeeming/exchanging skillbooks isn't an option. Maybe you can code an a|gorithm that somewhat "tailors" the prize to the user's account (without changing its value). During weekly maintainance, it can query specific database fields for an account (that would correlate to ninja upgrades or skillbreaking). If the values in those fields fall within a predefined range, the algorithm would return a negative value and this would trigger an a|ternate reward to be offered.
It's really a very, very easy and common database function, so it wouldn't take much time to implement and wouldn't cause any errors.

Thank you for considering my request.