Yumiko is an attractive girl with slightly wavy blonde hair that has bangs hanging over the right side, curly tips at the bottom and olive green eyes.
Yumiko's personality is pompous. Due to her popularity, she is held in highest hierarchy. Hence, she has no trouble making friends and also has little to no understanding towards people who have social troubles. Yumiko doesn't show interest, or mind anyone other than higher hierarchy of the class, which is noted by Hachiman Hikigaya by her attitude towards him. She holds herself in a very high esteem, and is not afraid to use her authority.
Most of males in her class sees her as a scary being. Hachiman once commented that her glare resembles an anaconda. It may be seen sometimes as if she forces her ideas onto the people whom she calls her friends. She doesn't like the idea of being opposed, turned down, or getting an answer not what she expects; this is shown during tennis court showdown, where Yumiko wanted to play tennis and doesn't heed to the words of Saika Totsuka, who got prior permission to use the court during lunch time.She feels that cooking and cleaning is old fashioned. In the light novel, she avoided cooking in summer camp in order to protect her nails from damage.Despite of the fact, she tried her best to make chocolates for Hayato Hayama.
It was mentioned by Yukino Yukinoshita that Yumiko wears expensive makeup. Yui Yuigahama also pointed out that her cosmetics and dresses are of high cost. She uses cuteness as crucial criteria in choosing friends with whom she hangs out with. She brushes off anything she doesn't understand as "making no sense".
She states her opinion on matters, and consider herself a genius for that. She forces her ideas on to others without concern for the individual, until Yukino pointed out Yumiko's flaws in her character: Yumiko imposes her one-sided opinion on others. From then on, Yumiko shows signs of change in her attitude.
She also shows genuine care for her friends, as well as children. This was first shown in Chiba Village summer camp for elementary school children, where she acts as an older sister for them, although she acts bossily. She also shows concern for Iroha Isshiki (Yumiko's love rival) when she was not feeling well after the ride. Hachiman describes her to be a queen or ferocious animal of the jungle who takes control, dictates and also cares for those in her boundary but hisses at those who aren't.
Despite her harsh and fierce personality, she is shown to be much weaker in emotional side. This is evidenced when she cried after a heated argument between Yukino and Yumiko for thirty minutes at the Chiba camp, which neither Yukino or Yui expected. In episode 12, her love maiden, along with her emotional side, is shown to the audience when she was reduced to tears in fear of loosing her clique and wished to stay together for a little longer.
She avoided Hachiman direction completely after he saw her tears in times of her visit to the club room. Her hobbies are shopping and karaoke.
Yumiko has be shown to be very good at tennis as it was stated that she won the Junior High Championship. She also demonstrated her skills in the tennis match showdown and she also participated in the athletic festival sports event of cavalry battle for the white team.
She is also a good actress that can put up a very convincing act. This was shown when she, along with Kakeru Tobe and Hayato Hayama, pretended to threaten Rumi Tsurumi and her peers at Chiba Village summer camp to break their relationship by exposing their selfish nature, as Hachiman Hikigaya intended. She despised doing it, and likely felt that Hachiman was seriously terrible for coming up with such a method.
She is also good at coordination, which is seen at the class play for the cultural festival. This is seen as a leadership quality by Minami Sagami. She dominates the class with her tone of voice. She can also play guitar in concert, which shown at the cultural festival. In light novel, it was mentioned that her skill includes tennis and nail art, She has some level of observation and understanding at least to the boundary of her clique.She filled the role of broadcaster of athletic festival event.
- "Hayato’s so nice…"
- The name Yumiko means "good, excellent" (優) (yu), "beautiful" (美) (mi) and "child" (子) (ko).
- Yumiko's surname Miura means "three" (三) (mi) and "riverbank, shore" (浦) (ura).
- Yumiko's special skills are tennis and nail art.
- Yumiko's hobbies are shopping and karaoke.
- When someone asks Yumiko how she spends her days off; she would answer: "Shopping, part-time job, and hanging out with friends without a purpose."