Summoned NFT characters can be sold after being sealed.

If your character has been upgraded after summoning, it is sealed as the upgraded version.

To 'seal' a character, you need to remove it from all of your team compositions and make sure that it is not currently training the the Screen Practice Room. Also, all items must be unequipped from the character.

* You can 'seal' a character through the game's NFT interface.

* 'Sealing' a character may take some time to complete.