Normal day setting. Then I guess AUs and genre switches are outta the question.
Okay, new ideas:
1. Competition. The Dokis, through a combination of confiding in each other, context clues, and light spywork, come to the realization that all the other members also want to pursue the Protagonist (damn, I'll have to give him a name) romantically.
With this in mind, it's pretty clear that the game is now first come, first serve. When he shows up, they all go to great lengths to flirt, get him alone, hint, before he's called over (or dragged off) by someone else. If you'd like more variety in what they could try we could set this plan of theirs during a school trip.
Eventually they're so focused on one-upping each other that they toss dignity out the window and start overtly trying to seduce him, or even giving him hand/blowjobs when the others aren't looking. Maybe two could temporarily form a truce and team up to "get an edge." Eventually, the whole thing could devolve into a compeditive orgy.
2. Game Night. If the whole "fighting over the guy" thing sounds distasteful to you (which I know it does to a lot of people), then a similar result can be reached without any bad taste of potential animosity.
Monika, always eager for some team building, has received approval from the school to use the club room after hours to get some work done, and has the members bring games. The thing that gets the ball rolling could be as simple as Truth or Dare.
3. I guess I could try out a Reverse Harem plot if the other two don't appeal to you at all, though my only stipulation is that the center of it would have to be either Monika or a FeMC. The harem would be the club, genderswapped.