>>6505307A) You don't understand charisma (it's not the ability to do silly things)
B) You're missing the whole point of Mirai; she's a character that markets herself as a serious wrestler. It's why she left TJPW, it's why she won't do the kuma pose and it's why she literally left the ring after Hanako freaked her out by being silly. Disliking Mirai for not doing silly things is like disliking Koguma for not doing death matches; they're not trying to do that.
C) Her charisma comes from how she reacts to silliness (look at her cutely bewildered facial expression 3 seconds in).