So I have this theory on the Vocaloid songs Crazy nighT and Bad End Night.

There was this mansion near a village and all the occupants were performing a play, then a villager (Miku) came to them because she was either lost or something. So the occupants of the mansion invited her in and they were all jolly but when it was time for Miku the Villager to rest and wake up she noticed that the time had stopped so she went crazy and panicky and tried to find a way out but the occupants said that all the people in the mansion are somehow bound to a script and they have to perform a play.

So Miku the Crazy Villager found the script. She read the end of the play and she didn't like what she saw. When it was time for the end of the play, the occupants could act it out because at the end one page has been ripped out of the script by Miku the Villager and so time stopped because they need to finish that play but without the ending they couldn't so they were stuck.

All the occupants of the house search for the script and later realise that it was Miku the Villager that ripped it out, she had read the ending page and didn't like what was written and she hid it. Since the ending couldn't be read and therefore performed everything was halted at a certain time. To finish the play the True Ending needed to be completed and that was the ending that was written in the script but it was hidden, Miku the Villager didn't like or think that the script had the real ending, in her eyes it was escaping, so she killed all the occupants.

The play however, just rewound until the start and kept repeating itself after the True Ending was not performed and every time it restarted so did everyone involved but not objects, for example the script. All the nights that didn't end with the True Ending were called Bad End Nights. Miku the Villager always thought that her escape was the True Ending because she was crazy and blinded by madness, she thought that the key to get out was the clock hand that stopped reading the time, she was however insane, so she killed all the occupants.

A figure stepped out of the shadows clapping and crying. That person was probably the Master and the Script Writer. The person cried and say that all the actors had put on a great performance and picked up a sealed letter of the ground. Every time that the play rewinds after the original Miku the Villager has a sealed letter when she arrives at the mansion.

And a note, because every time it rewinds Miku the Villager is crazy so she always gets Bad End Nights because she always thinks that she HAS to escape so she ignores the True Ending that was with her the entire time.

And a little thing that I noticed, there are 8 coffins in the secret room, there are 8 actors. They all keep dying.

Another thing, the True End has to be even more hectic, exciting, thrilling than the previous attempt. Plus in Crazy nighT when the hectic, rowdy feast was occurring the play made it up until 3 minutes till midnight while in Bad End Night was stopped at 4 minutes until midnight when it was only excitement when the occupants welcome Miku the Villager.

Final little snippet, the title had the infinity symbol so I can assume that because Miku the Villager cannot see the True End for what it really is the story will just keep repeating itself infinitely.