Madoka Ui operates as the dedicated Operator for Border's Kakizaki Squad, a moderately successful B-rank unit. She presents as a fair-skinned teenager of average build. Her wavy brown hair reaches her neck, with bangs covering her forehead, and her lips often hold a slight, feline curve. In her Trion Body, she wears Border's standard, functionally designed Operator uniform without personal modifications.

Ui exhibits a friendly, pragmatic, and optimistic personality. She consistently supports her squad members, offering encouragement during hesitation and maintaining a proactive stance in problem-solving. During Kakizaki Squad's match against Tamakoma Second, she displayed sharp situational awareness, providing timely enemy position warnings that enabled effective reactions to threats. Her pragmatic nature surfaced when she identified a vulnerability in her squad's rigid formation, proposing separate two-to-one maneuvers as a tactical solution.

Her core responsibilities as an Operator encompass battlefield monitoring, data analysis, and tactical coordination. Border's official briefing files document her performance parameters as follows:
- Trion: 2
- Mechanical Operation: 7
- Data Analysis: 7
- Parallel Processing: 8
- Tactics: 5
- Command: 6
This yields a total score of 33, underscoring proficiency in multitasking and real-time information processing, particularly her above-average parallel processing and data analysis capabilities.

Ui holds personal preferences for deep-fried tempura, chilled sōmen noodles, manga, and cats. She notably dislikes using laptop touchpads, indicating a preference for alternative input methods during operational duties.