Note: You arrive at the branch between endings after you defeat Fuujin and Raijin. Once they are defeated you a warped back into your soul world where Jeannette will ask you a question about your happiness which has a choice of two answers. To ensure the good ending you must respond with the "to live my life the way I want" answer at this this.
I begin this video at the final save before the final Battle with Kano in the Asuka Stone platform dungeon. This is the spot you receive after besting Fuujin and raijin. After some brief item usage to boost my status, I arrive at the final area with Kano who is content on destroying the world.
Since I didn't take the time to complete some of the final side quests this battle takes a little bit longer than it normally would. It isn't really too bad once you figure out the order in which to tackle each of the separate companions. I choose to combo all of my party members in order to increase the damage expended on the boss. Before killing any of the boss parts I took the time to have Anastasia take some pictures to add the bosses to her bestiary. If I did this again I would probably back track to get the panoramic lens so I can get all the enemies shots within one go.
You will note that I go after the Yasakani Gem first because of its healing ability, which nets it 800Hp per turn, something that is not too bad provided you damage him more than for each turn. After the Gem, comes the Yata Mirror and the Kusanagi Sword, the order is really up to the player at this point. I choose to go after the Yata Mirror because its frenzied surge hits all characters instead of the usual single character attacks of the sword. The sword is the last of the items to be destroyed but the strategy follows the same combo tactic.
My basic strategy for the whole battle is as follows. If anyone's HP drops to 50% or lower I usually have Blanca use aurora to heal the whole party. Next I have someone use a soul benediction to remove paralysis if it happens to land on a member who does not have a crucifix, like Anastasia. Next I combo everyone up to the last person who will have a move right before the boss's turn in the round battle order indicator. To achieve the best combo count and highest damage for my current party I utilize Karin's Geuschbench move, Blanca's soul comet (which put the enemy in the air), and finish with hard physical attacks from Yuri and Anastasia. With my party around level 61, it will net anywhere from 900 to 1,200 damage point which is enough to stay ahead of the Yasakani Gem's healing ability.
During this time Susano-o will attempt to combo once in a while. He will gather any of his attachments and you will receive the message "Susano-o is going for a combo". After announcing his intend you will have a complete turn to make preparations for his attack. I usually do any healing and buffs with the quicker characters, the ones which will get another move in before the boss's round. Once every character just has a single remaining move before the combo I have everyone defend. This greatly cuts down the damage you will receive from the combo attack and prevent additional chaining damage effects. In the worst case scenario your party will have to weather fearsome thunder, extinguish blow, frenzied surge, and final revelation. These are easily survivable if you defend; you can always have Blanca cure you following the round. These become less lethal as you kill off Susano-o's helpers.
Once you have just Susano-o remaining in the battle I changed up my tactics a little. First of all Susano-o is one of those bosses which isn't affected much by attacks that make an enemy airborne or knocked down. This means that you shouldn't have to custom tailor your combo attacks so much or take into account if the enemy's current elevation changed from the attack before. I have Blanca and Karin combo as before, but now bring out some of Anastasia's card powers like the power cannon and aqua rise (I think power cannon works better though). I also take the time to occasionally put up an arc barrier increasing my special defense. This allows my characters to weather a round of abuse and not have to constantly heal up with aurora. Each combo round where all characters can combo will land between 1,000 and 1,200 to Susano-o, allowing you to chip away at the 10,000 HP total a little more quickly.
Also during this time where you are trading hits with only Susano-o, you will occasionally want to take what I call a maintenance round where you take care of anyone's low SP or MP issues.
In this final battle no characters were knocked out or did they go insane from SP depletion. After the battle, I allow the good ending to play through along with the credits and epilogue.