Marika Mizushima is a university student who also works as a popular model. She is a member of the DJ unit Merm4id, a tropical-themed group within the D4DJ franchise. Her role in the group involves backup performance and dance, supporting lead vocalist Rika and DJ Saori. Marika possesses an easygoing and calm personality with a naturally comforting atmosphere. She is friendly and carefree, and despite her popularity and professional modeling career, she remains down-to-earth. When she entered university, she immediately drew attention, but she formed a genuine close friendship with Rika, who approached her without being intimidated by her status. This friendship is a key relationship in her life, and it was Rika who initially encouraged her to begin DJ activities. Although Marika has a gentle and relaxed exterior, she has a genuine passion for live concerts and approaches her DJ activities with seriousness and dedication. Her motivations stem from a desire to pursue new experiences beyond modeling, including a dream of becoming an actress. Her notable abilities include her skill in nail art, and she has a fondness for visiting cafes and eating fluffy foods like pancakes, though she dislikes salted plums. Over the course of the story, her calm demeanor remains a steadying presence within Merm4id, and she dedicates herself fully to the group's performances and growth.