I think fashion and colour analysis is one of my favourite things to write about.

Each character is Persona 3 each has their own individual colour attributed to them, in sometimes a more subtle way, or oftentimes it's a lot more blunt by just looking at their clothing or design. Mitsuru is no different! She sports very bold reds all over, starting with her vibrant and luxurious hair, and bleeding down into her uniform and even her eye colour. Akihiko and Shinjiro also share some red shades, making the three match pretty well as childhood friends.

Here's what I pulled from Crystal Cure:

Red is the warmest of all colors. Red is the color most chosen by extroverts and one of the top picks of males. On the negative side red can mean temper or anger. In China, red is the color of prosperity and joy. Brides wear red and front doors are often painted red. Red is Tuesday's color. Red roses symbolize passionate love. Ruby rings should be worn on the left hand. Red is the color of Mars. This planet is known as the God of War.

Red is associated with fiery heat and warmth. It can also mean danger (burning).

Red is the color of blood, and as such has strong symbolism as life and vitality. It brings focus to the essence of life and living with emphasis on survival. Red is also the color of passion and lust.

Okay! That's a lot to digest, so let's break this down by focusing on the italicized points.

  1. Anger: Mitsuru deals with a lot of anger, re: her father's death and guilt that he carried, making it one of the main focal points for her development. While this anger to many would fuel at others who have made her and her father suffer, this anger is directed at herself for not being able to help or stop what had happened. Mitsuru is far too critical of herself and thus blames herself instead of others when she gets hurt.
  2. Love: In her Social Link, Mitsuru is forced into an arranged marriage, and is torn between her wants and desires versus her responsibilities as future President of the Kirijo Group. It is one of the main struggles she is faced with in her link.
  3. Mars: I could go into full detail on Mars symbolism, but she shares many traits with it, including her more "masculine" personality, and her driven and oftentimes aggressive fixation on reaching her goals. 
  4. God of War: This is mentioned more in the information regarding her Persona's, but Penthelisea is the daughter of Ares, whom is the god of war.
  5. Warmth: Fleshed out in her Personality page, Mitsuru has a certain warmth to her during development, and becomes somewhat of a mother-type friend to SEES and those she holds dear. While the outside of her may seem cold and distant, she loves those who earn her trust with a fiery passion.
  6. Danger, Survival: This, of course, correlates to the danger her fathers faces near the end game, and to how Mitsuru struggles but ultimately is able to survive and come out stronger thanks to the help of her friends.

Aside from her school outfits, Mitsuru has a few other outfits she will wear outside of school activities. Both of them sport a black and white theme, which has an air of purity and, well, "badass-ery". One of such outfits is a snug leather jacket that suits her perfectly while on her motorcycle. Even her swimsuit is purely white with a large red flower on her shoulder. Her kimono and yukata outfits are opposite of each other, one being black and the other white, but they both share a similar flower pattern that boasts an air of maturity.

Mitsuru is also almost always wearing over-the-knee boots with her outfits, giving her a nice boost to her height.