Kirijo's Heir
Mitsuru is the only daighter of the wealthy Kirijo Takeharu. After he dies, Junpei mentions it must be hard for Mitsuru because she is the only daughter of Kirijo. This is especially important since many big company heirs are male. Mitsuru then becomes a secondary figure even in her own home because she is female. She is determined, however, to do what is best by her father's company (as has always been her goal). She outshines many of her classmates, she is the student council president, she's beautiful, she is in the spotlight whether or not people want her to be. This is particularly important in her social links in which we see her interactions with her fiance where she ends up behaving as though she is much more submissive than she is. It is only after her fiance insults protagonist that she stands up to him. This prodding is what makes her decide she can make her own decisions. She will still do what she needs to but will not be stepped on.
I feel this is an extremely important facet in Mitsuru's character because she is strong and capable. People rely on her, but she can often be weighed down by her own precieved weaknesses and shortcomings. She wants to do what is best for Kirijo group, but isn't sure she has what it takes to lead them. She missed the fact that she was leading SEES, although, she ran it muchmor effectively after protagonist joined. It is through their relationship that she takes on more determination and confidence, refusing to let anyone tell her what will be best for her and her company.
I enjoy that she finally gains the confidence to run the company. She can do what she needs to as we see within SEES. I think that as she is very practical and methodical that her company will flourish. In general, I feel her responsibilities are eased. This is because she is less focused on what she "should" be doing and instead just does what she feels is right. Her responsibility is still to Kirijo, but no longer at the detriment to herself.