I have "Next" button but can't do anything with it, it's just greyed out. That's what puzzles me
Thanks for mod explanation. It does have instruction but it wasn't clear to me where actually to copy it since instructions just say copy it to game folder and I don't see particular mod active.
When it says the game folder, it means the folder with the .exe files, mods with instructions as simple as that usually come prepacked in their install path so that you only have to copy whatever folder matches a folder in the same place as the .exe files, such as BepInEx.
If the next button is greyed out, there are only two possibilities I can think of at the moment.
Do you run the Kplug mod? If yes, does the school seem a bit dark like it is night time? If both answers are yes, that is because a special feature of the Kplug mod is to allow night as a period in the school if you get to around half of the time bar, I don't remember the exact requirements, but they are in the manual that came with Kplug. The only way to get out of it in this case is to go straight home, middle mouse button (click the mouse wheel) and hit the house icon, or let time expire and you will be sent home automatically.
If you are not running the Kplug mod, you might have been bugged out of being able to skip, in which case the only two options are to quit and lose all unsaved progress for the day, or however many days since your last save (I save after every single day for this reason specifically), or to hope time expires normally once the bar reaches the end and that the next period is either the end of the day or continues normally, meaning without the bug stopping you from hitting next.