Miki Jounouchi is the chief mechanic for the Sugo team, recognized for her technical skill in maintaining and optimizing racing machines. She carries herself with a tomboyish demeanor and has a noted appreciation for rock music.

Her significant professional and personal relationship with driver Naoki Shinjo began during his time as an F-3 racer, when she was impressed by his strong will to fight. After Shinjo entered a performance slump and developed a poor attitude, blaming his mechanics for failures, Jounouchi confronted him. She criticized his lack of respect toward the mechanics and his overall poor driving attitude, which became a catalyst for his recovery and return to form.

Their relationship deepened considerably after this event, making them indispensable partners both on and off the track. Romantic feelings developed between them over time. Jounouchi eventually transferred from the Sugo team to the Aoi ZIP Formula team, where she took on the role of chief mechanic and became Shinjo’s official partner.