Nanafa Kyan is a brown-haired, brown-eyed teenager living in Okinawa with her grandmother and two sisters. As the middle sister, she has an older high school sister named Nao and a younger elementary school sister named Kokona. The family helps their grandmother run the "Kame Soba" shop as part of their daily life.

Nanafa's peaceful existence changes dramatically when she witnesses a seal detach from a nearby Chinese banyan tree. This releases three confined spirits: the "jimunaa" spirits Niina and Raana, and Iina, an incarnation of an Okinawan lion statue. Their emergence introduces supernatural elements into Nanafa's world. More spirits soon appear, further altering daily routines. Unlike her naturally sensitive younger sister Kokona, Nanafa discovers this hidden world through the tree's unsealing.

Nanafa is energetic and experiences typical teenage life, including crushes—one mistaken for a boy who turned out to be a girl—and schemes like makeover strategies. Family is central: her fiercely protective grandmother intervenes when spirits disrupt Kokona's school events. Nanafa interacts regularly with her popular, caring older sister Nao and participates in family efforts, like trying various methods to cure a relative's cold.

Her daily experiences now intertwine with the supernatural. Mundane events—household issues like toilet malfunctions causing bathroom shortages, school sports days, beach outings, sharing ghost stories, birthdays (sometimes involving extraordinary gifts like castles), and typhoons—become complicated by spirit activity. The spirits, displaying traits like clumsiness, laziness, or specific dietary preferences, integrate into her existence, participating in both ordinary and extraordinary family activities.