Marina is a young Pokémon Trainer and Coordinator from New Bark Town in the Johto region. She began her journey alongside her two close friends, receiving a Totodile from Professor Elm as her starter Pokémon. That Totodile later evolved into a Croconaw and eventually into a Feraligatr, which she nicknamed Waniwani. Her other Pokémon include a Jigglypuff she calls Pink and a Misdreavus she calls Little Mis, reflecting her habit of giving affectionate nicknames to her partners.

Cheerful and somewhat flamboyant, Marina has a strong appreciation for cute things and enjoys dancing and singing. She has a playful, coquettish side and a notable fondness for men who wear capes, with a particular admiration for Lance, the champion of the Elite Four, of whom she keeps a scrapbook full of photographs. Despite this lighthearted crush, she is deeply loyal to her friends and is not afraid to stand up against threats. She is courageous in the face of danger but can be emotional and dramatic, especially when things do not go her way.

Marina's primary motivation is to become a Pokémon idol, a goal that involves putting on a show while battling, similar to the performances seen in Pokémon Coordinating. Her interest in flashy, synchronized moves with her Pokémon aligns perfectly with this dream, and she later becomes a Top Coordinator, recognized as one of the best in Johto. Her path into Coordinating appears to have formed naturally from her love of performance, and she eventually gains widespread recognition, appearing on magazine covers and even having her image printed on merchandise.

In the story, Marina plays a key role in the special The Legend of Thunder!, where she helps Jimmy and Vincent protect the legendary Raikou from the schemes of Team Rocket. During this adventure, she is captured by the duo Attila and Hun but remains resilient and is ultimately rescued thanks to her friends' efforts. Her role extends beyond this event, as she continues to appear in later series in cameos and references that show the growth of her career. She is seen watching the World Coronation Series battles alongside Jimmy and Vincent, demonstrating that her bonds with them remain strong.

Marina's key relationships are centered on her friendship with Jimmy, whom she has a clear romantic interest in, though neither directly addresses it. She also shares a close bond with Vincent, the third member of their trio, and while Vincent once tried to impress her by wearing a cape, her affection ultimately leans toward Jimmy. She gets along well with Eusine due to his cape-wearing style, but this is portrayed more as playful flattery than genuine interest.

Over the course of her appearances, Marina develops from a somewhat scatterbrained and idol-obsessed girl into a confident and accomplished Coordinator. Her journey from a novice trainer with a Totodile to a Top Coordinator and public figure shows significant growth in both skill and maturity. She maintains her cheerful personality but gains a more professional edge as she pursues her career.

Notable abilities include her talent for performing with her Pokémon, using coordinated movements and flashy techniques that appeal to audiences. She is a capable battler when necessary, as demonstrated during the Raikou incident, but her true strength lies in her showmanship and the strong emotional connection she shares with her Pokémon.