I don't know how, but chapters 4 and 5 of this story have been replaced with other chapters, so for now I'm giving you a couple of summaries of what's supposed to be here.
In Chapter 4, X is woken up by his watch alarm just before midnight, sneaks out of the house with a baseball bat, and meets up with Azalea. They begin walking to the park, until they run into Erika, who reveals that the real reason she went home early was so she could also meet up with a mysterious individual at the park at midnight.
When they all reach the park, the stranger reveals herself to be Knight Knight, from which the teenagers draw the conclusion that Undertale is real. From there, Final Froggit, Whimsalot, and Astigmatism arrive and propose teaching the teenagers how to use the powers contained within their human souls.