Yu is a voluptuous young woman who has purple eyes with white pupils, with elegantly long eyelashes. She has long, voluminous, creamy blonde hair reaching her waist, with two shorter strands curled to frame her face which are parted slightly to her left.
Her hero costume is composed of a purple and pale tan-colored skintight bodysuit, which is accented with orange stripes. The suit appears to have a pair of purple gloves with orange accents on the edge of the cuff. The design is similar for her "boots" which are cut off at the thigh in a deep v-shape. The suit also has three peculiar orange diamond shaped dots on the purple top that are located under her chest, and she also wears a purple domino mask with horn-like protrusions on the sides.
Mt. Lady is a young woman who seems to enjoy the attention that being a hero gives her and she doesn't feel any shame from having to take that fame from another hero while basking in the glory. She is also shown to be quite vain as she uses her ample sex appeal to further her popularity or to gain something. This vanity also shows a bit of shamelessness, as she isn't above making a lewd pun about her own body. During Minoru Mineta's internship, she also appears to be very lazy because she forced him to work instead of teaching him.
However, she is not careless, as shown that she will not transform into her giant form in confined spaces in fear of destroying nearby buildings and risk harming civilians as she is careful when fighting a villain who has taken hostages. Despite her vanity, she has shown to be selfless as she stopped Mr. Compress from reaching Izuku Midoriya's group after they saved Katsuki Bakugo even though she was already severely injured from All For One's attack. She also protected a group of civilians from All Might's Detroit Smash shock wave during her debut. This shows that despite her faults she is serious
