Save before entering the beach. Open savefile with texteditor.
On Windows save path is -> C:\Users\your_user\AppData\Roaming\Godot\app_userdata\High School of Succubus\saves
Search for "beccareveal". Change it to "beccareveal":true. Save the savefile. Load this in Game. This skips the Becca scene. Next Becca call you can trigger by multiply entering and leaving buildings, it has some random trigger.