'Kay. So even with a million Hades Rings I still got kicked all over the place. The damage from her opener wiped out all but my biggest tank, and from there it was death spam on my less protected characters and overwhelming my others. I did get a good 100 thousand off between a Master Spark and some fire based attacks, but it generally felt hopeless. Is this a power-through-it-before-it-powers-through-you fight? How did you handle it, exactly?
First of all, IMPORTANT FOR EVERYONE.
Trying the new translation patch broke my game. So make sure you have a fresh copy before you try to patch. It doesn't seem to like the previous translation patch (maybe it was just me). It didn't ruin my saves though (which I backed up of course), but just don't patch without first being sure you can re-install or whatever if it breaks it.
I take all boss fights fairly slow and steady. But first:
I just read the new translated manual, and apparently death(and poison and par, etc) resistance is multiplied by 3. so if your death resist is 35, you actually have a 105% resistance to it. It says some enemies have more than 100% chance to inflict these status ailments, but her nasty opener is a card you get when she's on your team, and it says "100% chance" so..yeah hopefully it's 100% for the computer as well.
Anyway, slow and steady for me, I think I have better defensive stats than most people.
Anyway, my "boss killing" team is always china,Remi,Reimu,Patchy. Now of course I swap people out occasionally, but that's the team I use to establish a fight.
Now I've leved a few times since that fight, and some of my gear was discarded in favor of hades rings and a ribbon, but here are my stats normally (skipping some to avoid wall of text):
China:
lvl 64.
5252 hp, 1666atk,997mag,3273def,1938mnd,149spd, resists average.uhh..160-170
Remi:
level 57
5126hp,4738atk (her dps is insane for me),2199def,2200mnd,659mag,185spd,resists average 135
Reimu:
level 65
3525hp,2131atck,3052mag,1660def,2512mnd,165spd, resists 180across the board cept mys at 112
Patchy:
level 57
1497hp,4401mag,4442mnd,132 spd, resists all 160 except spirit at 200, and mys at 332
Now generally I spam barrier with reimu until she's either out of sp, my buffs are near 100%, or when I need to heal someone soon (and her aoe heal would be inefficient). Generally my first swap is reimu after she gets 3 or so turns, I replace her with Minoriko..who is as important to boss fights as the previous four for me.
lvl 65
2945hp,2426mag,757def,2749mnd (I tried to make her had to kill), fire and cold resist at 140, the rest at 190
For the boss. I replaced my offensive gear with the death resist stuff. Not the defensive stuff.
I find in this game offensive stats win the trash, and defensive ones win the bosses >=)
sorry for spam, I'm just willing to bet you have a hard time because your defensive stats probably aren't as high as mine.
I wont go into strategy too deep. Of course I replace other people eventually for people like sakuya and such for speedbuffs etc. One thing I notice though is that my boss killers are wayyy beefier than everyone else, who typically get 1shot by a sneeze. So I always make sure I don't swap someone beefy with someone squishy until immediately after the boss uses a big multitarget hit. With this boss in particular that's pretty hard since most of her attacks have death. I waited until after that stupid "thrust" move though (which hits like a truck, but no death).
I noticed that this boss didn't really have that "I'm almost dead so I'm going to spam my strongest move over and over again now" habit that most of the bosses have, so hopefully you don't need to worry about that.