Kamome Sengakuji is a 13-year-old girl from coastal Osaka, living with her mother and stepfather after her biological father's death. She moves reluctantly to Akihabara to stay with her grandfather, Shimabukurou Sengakuji, who knows secrets of the Rosenkreutz Society. Her name, meaning "sea gull," reflects her Osaka origins.

Financially driven and resourceful, she uses her Pata-Pi device Billiken—a futuristic piggy bank and counting machine—to monetize personal details like her hobbies, preferences, and physical measurements among classmates. Kamome obsesses over her appearance, using padded bras to enhance her bust size, leading to rivalry with teammate Suzume. Her adaptable and calculating nature aligns with her AB blood type, though she reacts snobbishly if others doubt the Divas' capabilities.

Billiken transforms into the water-element Diva Amphitrite, deployed against enemies like Jun's Cerberus. Kamome awakens Amphitrite during a crisis by declaring herself an "Anima Mundi," a pure soul chosen to wield the Diva's power, integrating her as the team's fourth member. During the climax, Crane overpowers and seizes Amphitrite, leaving Kamome powerless until the Divas are restored.

In the *Summer Vacation of 2011* movie, her participation is reduced, but she joins the mission to the space fortress Metatrone. There, she achieves Astral Fusion with Amphitrite—an advancement beyond the TV series. This fusion enhances her combat, allowing her to wield Amphitrite's laser cannon in ranged and melee combat while wearing specialized armor. After Crane returns the Pata-Pis, she reunites with Billiken but laments its lost coin collection before returning to Osaka.