Satsuki Miyanoshita, an 11-year-old fifth-grader, relocates to her late mother Kayako’s hometown with her father and younger brother Keiichirou. Kayako, a revered exorcist, left behind a "Ghost Journal" documenting methods to seal spirits she once trapped—entities now freed by urban development. Initially dismissing the supernatural, Satsuki embraces her mother’s legacy after discovering the journal, confronting unleashed ghosts like Amanojaku, a demon inhabiting her cat Kaya. She strategizes with friends to re-seal threats, balancing skepticism with growing resolve.

Satsuki’s green eyes and reddish-brown braid—adorned with a pink bow—complement her practical red jacket, pink shirt, blue skirt, and black shoes. After enduring teasing, she adds shorts beneath her skirt. Standing 4’9”, her appearance mirrors her blend of youthful energy and responsibility.

Mature yet occasionally moody, Satsuki shields Keiichirou from their mother’s absence, managing household duties while masking her fears. She clashes humorously with classmates Hajime and Leo but proves resourceful in crises, employing the journal’s wisdom to outwit spirits like Akane. Her journey from doubt to leadership cements her as the group’s decisive mediator.

Her relationships oscillate between playful rivalry with Hajime and steadfast alliance with Momoko, a self-proclaimed born-again Christian. Spectral guidance from Kayako aids Satsuki during pivotal battles, such as defeating the entity Ohma through maternal insight and personal ingenuity. In expanded stories, she rejoins allies under Sora’s leadership to counter Ohma’s return, reaffirming her dedication to protecting both her town and her family’s supernatural heritage.