You know, that's actually a really good idea. I need to start actually doing things, anyway.
So... suggestions for how to start this off? A good beginning would be to pull together a roll call for people that'd like to take part in the main group storyline part: those who are content with what they've already put out for Day 5 can stay out of it and stick with what they've got.
Alternatively, there could be multiple main groups that get involved in the town, to segment the story bits into more manageable group sizes. Arranging who goes to what major events and why (or why not) will be one of the big challenges: I think most of those that went to town would notice the problem with the library, in particular: that could serve as a place to meet up again temporarily to rearrange groups for later events, even if some might be delayed too long to take part in the fight.
Now, what are the main events that happened there, and in what order? From what I can remember:
Chronologically-important events:
Morning
1. Breakfast, meeting with Saniwa, fake IDs
2. Bullying/bribing Reimu into a tour of the Covenant base, wyvern fight in the library
To Town
~2-3 timeframe: Mahjong vs. Yakuza, van theft
3. Idolm@ster contest; attacked by Oyuki, shadow-catgirl summoning, fended off and captured
4. Shadow appearance in Nate's bookstore, major fight, meetup
5. Encounter with Nue
6. Trainwreck of a train invasion, Amakawa, Byakuren+Co., exposition in the van
Evening approaches, groups return to shrine
7. Dinner, imperfect Eirin cure offered (mostly glossed over)
8. Wedding decision
9. Chibification (select people, no clear pattern)
10. Fight with Mima (already covered pretty well)
Time-flexible events for groups not interested in participating in certain events, or that would screw up continuity if they attended certain events:
Catgirlification
Shopping in town (clothing or otherwise)
VIVIT recruitment (current version was as part of/tail end of bookstore event)
What am I still missing?
I think the key now is to put together who absolutely has to attend certain events, who would like to, and start working out what groups of groups to split into and where they'll go, including filler events to work out time/location inconsistencies.
For me: Midori is mostly required for the breakfast and underground, then the idol competition and meeting with Oyuki. Nue meeting is recommended, but I could stand to avoid the train bit. Dinner needs to be actually fleshed out, more than anything.
'Signups' for where to be would be the current task, but I think I'll wait on formalizing that until I get some more input on significant day events and maybe ideas for filler/what can be shuffled around.
So, what am I still missing from that list?
EDIT: I have enough material for a post and a half of Day 5 Morning stuff, but I've yet to get around to filling in the talk with Satori I stalled on to talk with Gpop about. It should have no major impact on future events, aside from filling in Midori's stuff for that timeframe.
Though I should ask (again), is the shrine waterfall close enough for mana transfer via the shrine/base/generator?