well, idk if it's a known bug or anything, but when i was playing Nami.wav i replayed it again after winning (and some time after restarting the music again in the menu) and after completing it again, Melodii got stuck with Nami afterwards, even closing and opening the game (i guess mi only solution will be going in the options and deleting my progress in story mode)
https://drive.google.com/file/d/1HOlaf3t7Ch2nD2G8Tag5hyfp0bvavHWu/view