Wow... I actually got tripped up on saving the 2nd character (Kanji). I saw two rainy days and thought that's not enough to signal fog. And then it totally did.
I was like... fuck. But I had a save from 2 days prior. Too bad I was only on the 5th floor, hadn't even hit the mini-boss yet, and was like level 18 (with the dungeon main boss being level 27).
So then I feverishly worked through the last 6 floors of the dungeon in 2 days. I was out of SP by the end of the 2nd day (ABSOLUTELY the last day to save Kanji), had to use up some SP items, was only level 23 (and I had to grind to get to that point). The only reason I was able to eventually win the battle was a level 23 (+ S. Link) persona strong to physical attacks. The only reason I was able to beat the mini-boss was that he ran out of SP (I was probably 6 levels below him).
That was hard.
I'm never procrastinating on dungeon crawling again.
Impressions so far: The start of this game is more exciting than the start of Persona 3 (FES). There's more plot development. Persona 3 was rather aimless for like the first 15 hours. After that, though, it got seriously fucking awesome. I think I like the tone of 3 more than 4, though. 3 was a heavy fucking game in terms of plot and atmosphere. I mean, a hidden hour when everyone is transmogrified into coffins, while you endlessly scale a huge, endless tower of despair and hatred, stalked by Death at every turn? Plus, they kept evoking personas by shooting themselves in the head... fantastic. Persona 4 feels a little happy compared to that.