Overall, this is a highly polished game, especially in terms of its music, art, and gameplay.
I do have one minor suggestion: during the first phase of the boss fight, consider introducing more interactive events. For example, successfully dodging twice in a row or landing two consecutive hits could reward the player with a skill or an item. This buff could help players navigate the second phase more easily, giving them extra breathing room to observe and learn the boss's attack patterns. This would also prevent players from zoning out if they get stuck in the first phase for too long.