Let's make this simple.
ScreenStoryMode just loads everything from the StoryMode folder.
Every single lua inside this folder is a self contained screen.
The file that starts the story is named Init.lua.
Anything else doesn't matter, because you set the next screen, or the song, or whatever inside init.lua.
Set next screen using the VN_NEXT_SCENE variable.

## How to play a song after a cutscene?
Set the next screen as ScreenStageInformation and do all your setting in a lua inside StoryMode.
Set the global VN_NEXT_SCENE variable to the name of the story mode lua you want to be loaded after this.
