Assuming she is indeed a 3w4, Kira I probably isn't one though he probably has it in his tritype. Lets take the core definition of both the two types:
E3Ones are conscientious and ethical, with a strong sense of right and wrong. They are teachers, crusaders, and advocates for change: always striving to improve things, but afraid of making a mistake. Well-organized, orderly, and fastidious, they try to maintain high standards, but can slip into being critical and perfectionistic. They typically have problems with resentment and impatience. At their Best: wise, discerning, realistic, and noble. Can be morally heroic.
I think Kira has more common with e1 than e3 for sure and there is one thing I hope you've noticed in Kira to prove a point of mine which is Kira isn't overly concerned about their image though he does have a perfectionist drive in him which makes him somewhat image conscious.Threes are self-assured, attractive, and charming. Ambitious, competent, and energetic, they can also be status-conscious and highly driven for advancement. They are diplomatic and poised, but can also be overly concerned with their image and what others think of them. They typically have problems with workaholism and competitiveness. At their Best: self-accepting, authentic, everything they seem to be—role models who inspire others.
The difference in the e3 image consciousness and the e1 image consciousness is that the e3s are driven by their need to create a certain image; whereas the e1s are internally driven to maintain integrity which might make them concerned about maintaining this image.
And I believe Kira is the latter.