I'm a little lost on how much we can do with this item. It certainly sounds handy, but I don't want to write out an S-Link making use of it if it's not going to work. Here's a basic outline of what I'm looking to do:

1. Go to Library on lunch/evening slot - No Twilight
2. Get a text from Twilight inviting you over to her house (is opening a new area or meeting at library easier?) for an evening-only event
3. Go and S-Link happens

Is this possible?

That's 100% possible.

Right now whenever an NPC is supposed to spawn the game does some quick checks to see if they're supposed to be there, if you're ever in the library on weekends for example, Twilight will not appear.

So it would be easy enough to also have it check if your s-link is at a certain level, and remove her accordingly.

Opening a new area is also just fine.

The only part of this represents any challenge at all on my end is building an inbox for the player to receive messages on, but that's no real heavy workload. Feel free to write it, I'll work on incorporating it

Thanks, as long as it's not too  much work. Just figured that it's a demo and showcasing what's available is important, so I wanted to get an idea of what is and isn't possible.