Isami Hanaoka is an 11-year-old girl of Japanese descent. After spending her early childhood in the United States, she relocates to Japan to attend Oedo Elementary School. Her family lineage traces back to the historical Shinsengumi, descending specifically from Kondō Isami, her namesake. This heritage takes center stage when she discovers a hidden basement in her ancestral home containing artifacts left by her ancestors, including the Dragon Sword. A recorded message from her forebears reveals her destiny: to unite with fellow Shinsengumi descendants and combat the ancient enemy organization, the Kurotengu (Black Tengu).

Her personal history is marked by the unexplained disappearance of her father, Kai Hanaoka, a physicist researching the energy mineral Luminotite. He vanished to protect his family from the Kurotengu, adopting the concealed identity "Wild Rose Man" while secretly monitoring Isami’s safety. This absence fuels her resolve to uncover the truth. She lives with her mother, Reiko Hanaoka, a newscaster, and her grandfather, Kanyusai Hanaoka, who manages household duties and later becomes a vigilante ally.

Isami possesses a tomboyish appearance, characterized by short, spiky shōnen-style hair and a preference for practical clothing suited for athletic activities. She excels both academically and physically, demonstrating proficiency in martial arts, karate, football, and biking, earning recognition as one of Oedo Elementary’s top athletes. Her personality blends determination, empathy, and a strong sense of justice, often prioritizing others' safety. As the de facto leader of the Shinsengumi descendant trio, she coordinates strategies and motivates her teammates during missions.

Key relationships define her journey. She forms a close bond with classmates Toshi Tsukikage and Soushi Yukimi—fellow Shinsengumi descendants who wield the Dragon Eye and Dragon Fangs. Their partnership evolves from initial friction to unwavering camaraderie, balancing their roles as warriors with school life. She maintains platonic friendships with male peers while navigating typical school dynamics, including interactions with classmates like Miho Shimada. Her homeroom teacher, Haruka Takagi, a descendant of the Rumi clan and covert kunoichi, provides guidance and support against the Kurotengu.

Isami’s primary weapon is the ancestral Dragon Sword, activated by the invocation: "The Dragon is the symbol of justice; while there is evil in the world, we will fight in the name of Good. Shinsengumi, forward!" This weapon channels Luminotite energy, converting emotional and mental resilience into kinetic force for combat. Her fighting style blends swordsmanship with athletic agility, often leading confrontations against the Kurotengu’s forces.

Her character arc focuses on reconciling her dual identity as a student and protector. Initially adjusting to Japanese culture after life abroad, she grows into her leadership role through battles against the Kurotengu. These conflicts involve uncovering secrets about her father, the Kurotengu leader’s extraterrestrial origins, and the broader conflict involving brainwashed agents and alien technology. These experiences foster maturity, deepening her commitment to justice and family legacy. By the series’ conclusion, she emerges as a more resilient and principled figure, having strengthened familial and communal ties while honoring her ancestors’ mission.