Mythril, also spelled Mithril, is a supporting character in the anime Flaglia: Natsuyasumi no Monogatari. She is a bright and cheerful girl with a friendly personality, quickly becoming well-liked by her fellow summer camp attendees. Despite her carefree attitude, she is a highly capable fighter, possessing notable strength and agility. Mythril is also highly intelligent, with a keen eye for detail, and has a deep fascination with technology, particularly robots and machinery. She spends much of her time tinkering with machines, and her technical skills prove valuable as she builds and operates various devices to help the group overcome obstacles on the remote island where the story takes place.

Mythril's personality is marked by a strong sense of loyalty and protectiveness toward her friends. She is often anxious and prone to worrying about the safety of those close to her, sometimes doubting her own abilities. This anxiety drives her to be fiercely dedicated, willing to put herself in danger to ensure the well-being of others. Her need for security and belonging makes her rely heavily on the support and affirmation of her allies, and she can become suspicious of those she perceives as threats. Throughout the series, her bravery and determination are tested as the group faces various challenges and dangers, and her unwavering spirit reinforces her role as a reliable and heroic figure among the campers. While her exact background is not elaborated in detail, her motivations are rooted in protecting her friends and using her technical expertise to contribute to the group's survival and success. Her development involves learning to manage her anxieties and trusting in her own judgment as much as she trusts her companions. Notable abilities include her combat prowess, her technological ingenuity in constructing and operating machinery, and her sharp analytical skills that help the team strategize and solve problems.