=First enemy=
Being the first of the humans you face, he's honestly nothing too special - that is, other than how he's tougher, stronger and faster than a good chunk of the bosses you've fought so far, being stronger than some 3* difficulty demon bosses. This trend will predictably continue through the rest of the human enemies; they're the final storyline bosses after all. Also, you have a limited number of KOs you can receive here, so try not to get downed.
He frequently uses your 18TP move, which drains MP and causes poison on top of damage, so carry precautions to cure poison and/or dodge/counter the attack. Other than that, he also has a Stumble-causing multi-hit move, so equip the accessory that grants 99% stumble resistance or you're going to have a bad time. The rest won't be different than most other bosses - keep your HP and MP scores up, handle his attacks and whittle down his HP gradually.
When you reach phase 3 and he gains TPMAX, heal up. Don't dodge or block, heal up. This is because his ultimate takes effect the FOLLOWING turn. After healing up, equip as many DEF+ items as you can (don't forget stumble resistance!) and guard the incoming undodgeable. The rest should be the usual fare.
=Second enemy=
The first thing you should notice is that she hits HARD. Aside from the mostly-harmless but stumble-causing earthquake spell, all her attacks are powerful spells that capitalize on her high magical stats, and since they're magical neither DEF nor dodge will save you (though guarding can mitigate the damage you receive). Get fire resistance and electricity resistance items and equip them, and also equip the スタンガン for faint resistance - you do NOT want to get stunned at an inopportune time. Don't forget the stumble resistance boots, either. Additionally, pay attention to her sprite. As one of the comm sequences will reveal, closed mouth means incoming thunder spells, open mouth means other moves (fire, earth or a TP/MP restoring move). You have limited KOs here too, so play it safe and whittle her health down carefully.
(As a note, you can actually drain her MP to 0 if you spam the 18TP move enough, which renders her harmless until the next time her AI decides to use spiritual concentration).
When you reach phase 3 of the fight and she prepares her TPMAX move... Equip all the dodge+ accessories you have and backstep, in contrast to the rest of the fight. Hopefully you'll avoid all of her ulti's hits; if you survive, you've won.
=Third enemy=
As some of the comm sequences will reveal, he's quick, but his attacks aren't especially threatening: your 11TP two-hit slash, a counter move he can do at around TP50, and your 15TP ground-wave is probably the most frequent attacks he'll do (don't forget the anti-stumble boots here, either). He can use the doppelganger spell though, which is a cue that the next turn he'll use the DEF-ignoring 22TP move. It's powerful, but slow, so you should have the time to either attempt to Stumble him with the earthquake spell or ground-wave skill (equip accuracy+ accessories for insurance) or counter with the 35TP iai counter. Just keep your HP/MP up and whittle his HP down, like the previous 2 fights.
When he hits phase 3, however, he'll pull out a machinegun. Equip all your dodge+ items now. He won't attack straightaway, but spend a turn to give himself a buff; use this chance to do whatever. Afterwards, spam backstep for several turns in a row, until Mayuko comms in and tells you to attack (This will be when she counts to 100).
He'll spend 3 turns reloading, so use that time to wail on him. Rinse and repeat - the rest of the fight is just "backstep until he starts reloading and beat him down when the chance comes up".
=Fourth enemy=
WARNING! After you finish this fight, it's a one-way trip to the final boss.
Heavily scripted fight. First things first: Setsuna is FAR out of her league here, she'll get shishkebab'd unless you somehow have insane stats or something, and even then it's uphill. As long as her MP isn't 0, though, she'll auto-revive herself each and every time she ever gets downed (note that there's no limit to the amount of times you can get downed here), so keep your MP up and weather through the fight. Eventually you'll enter a point where both sides will just spam ultimates at each other without your input, the battle ending shortly afterwards. Oh, remember how you can still use your ultimate even if you're downed. You'll be using it manually soon enough.
=Final boss=
The first part of the battle is actually a relatively standard boss fight. The boss has several moderate-to-powerful attacks, but by now you should have enough practice with standard bosses - similar strategies apply, more or less, and she doesn't inflict many ailments either. Just whittle her HP down while keeping yours up, though take note that you'll probably need to keep your MP high to full for the next part.
When the next part hits and both parties are automatically filled to maximum TP, don't pull any punches here. Use the 100TP move, and ONLY the 100TP move. The boss' ultimate will crush all resistance and down you without fail, but you should have a sliver of MP left for your ultimate, which endures any assault, to go off and fill your HP and MP back to full. Keep repeating this until the next part of the battle - you'll know when you get there. The fight's pretty much over at this point, go do whatever until you're treated to the ending cutscenes.
