Ako is a 9-year-old student in the third year of Public Kanon Elementary, who is in the same class as Kanade's little brother, Souta. She is very mature for her age, but also very cold and not above handing out lectures to her elders, particularly towards Hibiki and Kanade. Unbeknownst to the Pretty Cures, she had masked herself as a mysterious fighter named Cure Muse who aids them using colorful piano keys to form barriers and restraints. She often assists the Pretty Cures if they are trapped, but leaves them to finish off the Negatones. She hid her status under the mask and did not speak, as her Fairy Tone partner, Dodory, did all the talking. She often declared that she won't partner herself with the Cures until the time was right.

During Episode 35, she reveals herself to be Major Land's princess, the daughter of Aphrodite and Mephisto. After her father went missing, she ran away to Kanon Town and disguised herself, living with her grandfather, Otokichi. When Mephisto stole the Legendary Score, Ako's potential as a Pretty Cure awakened. As Cure Muse, her short orange hair grows to knee-length and gains two yellow ribbons on each end. In her masked form, her theme color is black, and in her true form, her theme color is yellow, and her Fairy Tone is Dodory. She doesn't have a main weapon, but she uses her secondary Fairy Tone, Tiry for her purification attacks. She is the youngest Pretty Cure in the franchise to date.

She introduces herself as "Playing the Goddess' tune, Cure Muse!" (爪弾くは女神の調べ！キュアミューズ！, Tsumabiku wa megami no shirabe, Kyua Myūzu!)