Kumi Okazaki is an eighth-grade student, approximately 14 years old with a birthday on March 9, who attends the same school as Tokoha Anjou and maintains a friendship with her. She possesses pink hair and violet eyes. Her personality is sweet and gentle, often appearing with a smile, though she can exhibit shyness. Despite initially being a novice in the Vanguard card game, she demonstrates a natural aptitude for understanding gameplay mechanics and can strategically overwhelm opponents.

During the events of Cardfight!! Vanguard G: NEXT, she joins Tokoha Anjou's newly formed team "Jaime Flowers" alongside Satoru Enishi, coached by Jaime Alcaraz. The team name is chosen by Jaime without direct input from the members. Jaime Flowers competes in the Under 20 Championship against teams formed by former members of Team TRY3.

In cardfighting, Kumi utilizes an Oracle Think Tank deck centered on the Battle Sisters sub-clan. Her deck composition includes units such as Battle Sister, Cocoa (Grade 1), Battle Sister, Marshmallow (Grade 2), and Battle Sister, Mille-feuille (Grade 3). Trigger units in her deck are Battle Sister, Ginger and Psychic Bird. Her G-Units feature Excite Battle Sister, Miroir and Soaring Auspicious Beast, Kirin.