This is a hack of the JP version of Castlevania Legends, known as Akumajou Dracula: Shikkoku Taru Zensoukyoku. It changes many sprites. Background, main character, enemy, items, etc. The main characters whip was replaced with a sword which shoots a wave instead of a fireball when powered up.
Database match: Akumajou Dracula - Shikkoku Taru Zensoukyoku - Dark Night Prelude (Japan) (SGB Enhanced)
Database: No-Intro: Game Boy/Color (v. 20210227-015730)
File/ROM SHA-1: BAAA12BE322ADC005E51B43C73A352420D7CD034
File/ROM CRC32: 4825B25F