Minamo Katsura is the younger sister of Seina Katsura. Both sisters share a familial link to the Jinguuji bloodline but lack its associated powers. Minamo is 13 years old with light brown hair, brown eyes, a birthday on April 4, and blood type O.

She lives with a significant congenital heart condition causing physical frailty. Minamo actively conceals this condition through persistent mischievous behavior and frequent pranks.

Her personality is creative and mischievous. She demonstrates a strong interest in artistic activities, particularly scriptwriting and drawing. Her creative projects include developing a trading card game and attempting theatrical productions like the play "Space Alien," though these achieved limited success.

Minamo first meets protagonist Rino Rando during rainy weather. Their encounter escalates into a two-hour argument fueled by Minamo's intense desire to possess Rino's hand puppet companion, Pucchan. This conflict ultimately establishes an unconventional friendship between them.

Minamo operates within the Covert Squad division of the Best Student Council. Her specific responsibilities within the squad remain undefined.

Seina Katsura later reveals Minamo's heart condition to Rino, explaining that Minamo's mischievous actions serve as a deliberate mechanism to distract others from her health struggles and physical limitations.