I do not disagree with the fact that The Shadow of Mitsuo is memorable or that the fight is important to the plot. That is the reason why I detailed that it's not a horrible rank (very similar to, but better than, the Ull situation from Valkyrie Profile: Silmeria). However, when DarkHolyElf stated that it should be ranked by the most recognizable name, there is a bit of an odd conundrum here. I'm very much for ranking characters over battles. However, I do focus on the character being ranked - this is an odd circumstance, as there's a bit of a case that the two are equal - however, if Mitsuo were, say, in control of the Shadow, I wouldn't have a problem. I don't support ranking Lyon (correction - proper grammar is "didn't") from Fire Emblem 8 because Lyon is never fighting in-game, it's Fomortiss using his body. I consider Lyon in the DL to be Fomortiss, and thus allow the final form of Fomortiis for this.
I cannot comment, nor will I comment, on Mana Khemia: Fall of Alchemy, as I have not played the game.
In Shin Megami Tensei: Persona 3, one of the character powers that awakens is the power of the persona. This is an aspect of them they are completely (generally) in control of. They can access it when they want, how they want.
I am not saying that The Shadow of Mitsuo is devoid of plot development, and I never have. Mitsuo is not in control of his shadow before or after the battle. There's a Final Fantasy Tactics character (and I cannot remember who specifically) we have ranked that people have argued about ranking the demon form only, because it seems to them that the power of that character arises from the demon purely. Or not allowing skills because they are associated with a power that is not theirs, is focused on the environment, etc.
It is a, probably in the end, very minor distinction, but I feel it opens up the door for very odd arguments that people have stated, in the past, they are eager to avoid. It makes me think of ranking Zelos from Skies of Arcadia, and using the final, final fight where he's merged with Ramirez. Yes, the battle does say it is Ramirez being fought, but it's Zelos in control of Ramirez's body, there, plotwise. It's a bit of the opposite take on this case, but it's a relatively similar concept.