Sara Kannazuki joins her childhood friend, Ushio Hayama, on a journey to a tropical island inhabited by her relatives. She actively participates in the group's primary mission: diving to locate the legendary Blue Butterfly Fish. Sara embraces the island life, engaging in swimming, diving, and socializing with both the group members and local residents during this quest.

She sports blonde hair and is consistently illustrated wearing swimwear or diving gear, reflecting the tropical environment and underwater focus of their activities. Her bond with Ushio is close, anchored by their shared history and the current expedition, though its precise nature remains undefined.

A significant perilous event defines her experience: Sara becomes trapped in a rapidly flooding underwater cave after misplacing her breathing apparatus, necessitating a critical rescue operation led by Ushio.

Details concerning Sara's background beyond her link to Ushio, deeper motivations, personality traits, or character progression across official media remain unavailable. Her role centers on her involvement in the central Blue Butterfly Fish quest and interactions within the group during these depicted events.