Itsuki is in the second year, the student council president and the grandchild of the current principal of Myōdō Academy. Itsuki appears to be a gentle, handsome, and athletic boy with a princely demeanor who attracts many subordinates and fans. At the beginning, Tsubomi developed a temporary admiration for Itsuki until discovering her female gender. She cross-dresses due to her having to substitute as the heir of the school and dojo in place of her ailing older brother, Satsuki. However, she maintains a great love for cute, girl things and is convinced to join the fashion club. In the events of Episode 22, she picked up Potpourri and thinks it's cute. She later becomes Cure Sunshine to rescue Tsubomi and Erika from danger with Potpourri while saving her brother's Heart Flower. As Cure Sunshine, her theme color is Gold and her flower symbol is the Sunflower. Her powers are related to the sun and can use auxiliary attacks in addition to her finishing attack. Her catchphrase is "I will heal the darkness in your heart with my light."

She introduces herself as "The flower bathing in the sunlight, Cure Sunshine!"