The Japanese version of Castelian reskins some of the sprites to turn it into a licensed Kyoro-chan (mascot for a snack called ChocoBall) game. However, this version suffers from a nasty buzzing noise generated by the DMC channel. This hack removes said buzz to improve the experience.
Database match: Kyoro-chan Land (Japan)
Database: No-Intro: Nintendo Entertainment System (v. 20210216-231042)
File SHA-1: AF568E157B76A61DA9B92B2FD2F219CC6E171C90
File CRC32: 61202FE9
ROM SHA-1: F0D4A36B8BAC7ED47978CE9C8A308AE0ABF0E768
ROM CRC32: 5229FCDD