it's better if more people than just me know how to work it.
The big invisible button overhead is a toggle for the UI: click-on, click-off.
Moving to a new scene will auto-hide the UI
Any questions, just let me know! And if you find any bugs, please tell me. I tested extensively but if I've missed something, I'd like to fix it for you.
Update to user guide: (shortcut) In the Cherry/Heart choice scene, on the chair back, there's an invisible button to go "back" to the start of Ep2. (or use UI)