Kintoki Sakata, born into nobility during Japan's Heian period, was disguised as a boy from childhood by her father to shield her from her uncle Yoshinobu's ambition to seize their clan. Yoshinobu orchestrated a violent coup, slaughtering her family at Mount Ashigara in Sagami Province. Minamoto no Raikō intervened, rescuing Kintoki and taking her to the capital.

Living continuously under her male identity in the capital, Kintoki joined Raikō's warrior band, the Shitennō (Four Heavenly Kings). Trained in combat, she specialized with an axe and earned the warrior name Kaidōmaru. A tattoo of the character for "Flames" adorned her upper arm, signifying her role. Over five years, she aided Raikō in defending the capital against disease, banditry, and political turmoil, developing deep, unspoken feelings for him.

Her past resurfaced through her cousin Ohni-hime, who led the Oeyama bandits as Shuten Dōji. Unaware of Kintoki's true gender, Ohni-hime sought to "rescue" her. Ohni-hime allied with Fujiwara no Michinaga, using bandit assaults to destabilize the capital for political ends, culminating in Kyoto's burning and Kintoki's abduction. Raikō pursued her to Mount Ōe, resulting in a confrontation that resolved their fates.

This character reinterprets the folk hero Sakata Kintoki (Kintarō), traditionally male. Key adaptations include the gender reversal, the tragic familial conflict, and the exploration of concealed identity within a historical-political context.