Thanks to some hugely appreciated assistance from one Felician, I am now 1/6 towards my goal:
Ariel, Izuna, and Felician hanging out by Ankan Shrine. I don't know why my characters keep getting locked in that stance though. It happened with Virtual Demon yesterday, hence the middle picture in my previous post. I don't press anything, best I can tell, but they end up stuck like that anyway.
Now, will I succeed in unlocking Izuna for Spirit Sabre tomorrow? He's cleared Kurama, and I think he's done Repairing Benkei as well, so he should be able to. Albion will have to do a little work before she can though. She's currently grinding Youen for better Golden Eyes, but once done she'll blaze through the last few Kyoto quests in no time at all really. She's more or less guaranteed to one-shot Odin. Everyone else... well that could take a while. Kotori's almost in Kyoto, just got a few side quests to do. Dancer Lancer can get there quickly too. Yuriko's about to wreck Izumo. Then the others are further back. Warlock Warlord is gearing up for Room of Rites. Scarlet and VR Nightmare are preparing to hit Yamataikoku. Serenity's gearing up for Tiamat while Sora is about to go to Kumaso. I'd like to get them all to clear Kyoto and unlock Izuna by... March 3rd... but that might be pushing it a bit.