[@Zeroth]: Once more unto the breach!

Mika first.
[list][*]Re: Personality stuff (again):
I feel like the way she probes people out should have been explained better in the form in this case. Her outward-facing mannerisms make sense when presented in this context, but at a glance they didn't really read as such.
Next point: I feel like if you want to have information hidden from the rest of the cast in a character, you contact the GM and discuss matters privately. A form (as I see it) is a third-person omniscient 'summary' of a character that other people (not just the GM) should have access to in order to understand the character, which means that you want to have most of the cards you want to play on the table when putting it up, so to speak. If it IS public knowledge, though, I think that it's reasonable to expect players to not metagame and know information that shouldn't explicitly be "public knowledge" in-universe.
Third part loops back to the first; it's a lot easier to make sense of things (and leave other traits to be developed further) if that first part is made clearer.
[*]Honestly, names to differentiate them from the "standard" would be better in my opinion. You don't need to denote a barrier as something part of a "barrier style"; it's a barrier, and reiterating that fact would be redundant.
[*]I think that onmyoji would generally grow by either expanding those reserves or becoming more efficient in it's usage, yeah, but that's a bit of a smaller point to make here. Translating magical energy into ether is probably fine, though, given how traditionally onmyoji would have shikigami (like, the non-paper familiar types) anyways, so that's probably an okay route to go down.[/list]

Re: Kyozan:
[list][*]Levitation and airdashing is probably fine, but I'd definitely try to lean more into the 'skill/speed' over 'strength' relative to one another as a means of differentiation. Arrogance explanation is fine, though.
[*]Both are problems here. A relative timeframe as to how long he lived would make it easier to judge, but hitting that cap in the assumed timeframe definitely gets you noticed.
With regards to the Big Three and a bit more quantification: I'm obviously using Shuten-Douji as a point of reference towards Kyozan specifically, and in-universe he would've had the capability to, say, cleave giant holes in the land with a single swing sort of deal, or bash through fortifications without worry—that sort of power, more or less. A canyon by the end of the fight, especially if it was large enough to be called a canyon in the first place would definitely place you on that level of power imo.
An acceptable level of power, though... If we're talking late Heian Japan? Probably sacked a few cities on his own. Mass murder, destruction, the works. Maybe even took out a small army or something in the process; something like that.
[*]Regarding age: I'm using given age as a frame of reference. The closer we are to a proper number, the easier it is for me to gauge how strong or weak a youkai would/should be. Again, with 1000 years being late Heian Japan and the age being listed as 1000, things didn't exactly line up as well. The bigger problem in this isn't that he was sealed for all that time, but how strong he managed to get BEFORE being sealed... Which, like, we're sorta resolving anyways?
I had initially mentioned the age not to argue the point that being older would make him stronger, but that he was way stronger than he should have been before being sealed. With the 150-year active lifespan as a point of reference (and a good chunk of that on the run from India all the way through China and into Japan, which sorta limits how much of a bloody trail he can afford to leave behind), he definitely had a higher floor than most of the cast (in his initial iteration, at least). 
[*]Re: Motivations: I think it works better, but again, need that in the history section. Wasn't present in the initial draft. Also probably more elaboration as to why things changed, but that can be done fairly easily with this in mind.[/list]

Uh... Yeah, think that's about it on my end.