The Master Key Seller Kopiya (合鍵屋コピヤ in japanese) is a Chu-Teng creature. He makes his first appearance in the star palace, and you will find him locked up in a cage, which he was put in due to making too many key copies. After you free him, he will let you use him to copy a key for free, but just one. As of his last appearance, he currently resides in the star palace.