@Chi-Lord Then who did? If it's an indie musician or otherwise not tied to some major label, they may allow you to use their song in a video the same way they allowed your VTuber partner to sing over it. Ask them if you're unsure.
But if it's one of them big-label commercial songs with a karaoke version, maybe don't use it here, just in case they take it down.
Anonymous-Frog
Who made the original audio?
Chi-Lord
i did not make the music.