Mari has purple lightning bolt-shaped streaks in her otherwise straight, black hair. Her calves and feet are unusually large. Mari also wears noticeable hearing aids.

(Born to Run - Thunder Road aspect) - Born to Run is a pretty lackluster 'superspeed' quirk, allowing Mari to run significantly faster than the average human. This also makes her legs and feet slightly tougher than average. In a moment of desperation, Mari unlocked the 'Thunder Road' aspect of this quirk, allowing her to double her normal top speed and generate electrical arcs in her wake. The faster she is going, the stronger the lightning.

Mari was raised by a typical deadbeat father; her mother had left before she could remember. Mari has the same quirk as her father, and his words to her were always, "You can't outrun me." An abusive drunk, Mari's father made her life a stoic hell. At school she struggled to hide the details of her home environment while trying her hardest to secure good grades. At home she did chores and tried to placate her father's sporadic wrath. All attempts to escape failed. Except for the last time. Mari discovered a previously unknown aspect of her quirk, something her father had never discovered, Thunder Road. In her final attempt to escape him, in a shining moment of pure freedom, she abused Thunder Road, an effort that has rendered her extremely hard of hearing. Now she lives on her own, taking care of herself, and trying her hardest to become a hero.

Mari stands tall, her over-sized legs giving her a bit of extra height. her height combined with her long straight black hair, and her amber, sharp gaze of disdain gives her the air of looking down on others. Mari is severe and judgmental, with a tendency to be condescending to those who she thinks are wasting her time. She is a perfectionist and places high value on individual effort and independence. She doesn't believe that systems, environments, institutions, or fate can truly stop a motivated individual and won't accept that excuse from anyone. She refuses to let her past hold her back, and expects the same of others. Mari is driven when it comes to her goals and will do whatever it takes to achieve them, though she is too straight-forward to be a schemer. She is highly-organized and takes great notes. She supports herself with a part-time job as a cashier at a convenience store.