When I say apparent I'm not talking about any mental flaws that all characters have, that comes with having a personality, and would be like trying to define perfection everyone has their own definition of that it's a very subjective thing. I mean that no matter what Kawakami Momoyo tries to do she inevitably succeeds in. Yes we do hear that she is bad at studying, but never once have we heard of her failing at something even if it isn't fighting she simply has no visible flaws.
Meanwhile
Point is unlike these two Momoyo does not know failure. Same for certain characters such as Hume or the Kuki clan itself who pride themselves on being perfect.
I know that Momoyo has some mental flaws but unfortunately I am unable to find being otherwise infallible very endearing or sympathetic.
Her grandfather did fight her in the Kazuko route and supposidly he wasn't holding back.
I think that hume also fights her in A-1, but