The story begins with the protagonist, Rin, waking up as a baby in a new world. She discovers she has been reborn as a cat-person, with black fur, cat ears, and a tail. Her new parents are Dan, a cat-person who resembles her, and Lyral, a human woman. Rin quickly realizes this is an isekai, a world different from her past life where she was a human girl named Suzu. She recalls a conversation with her dying childhood friend, Riku, who wished to be reborn as a turtle in another world, along with their friends Riai (a bird) and Ryu (a dragon). They had even agreed on a secret code, "Ri4," to find each other.
Rin's new life unfolds in a town called Dahl-aima, a mining town in the Haku-san territory. Her father, Dan, works as a town guard, a job Lyral helped him secure after he transitioned from being an adventurer. Lyral herself is a highly capable individual, serving as the secretary and bodyguard to Lord Targats of Haku-san, and is currently on maternity leave. Rin observes that this world is populated by beastfolk, and humans are rare. She also learns that magic exists, a fact that further solidifies her belief that she has indeed been reborn into the isekai her friends had dreamed of.
Rin's past life memories resurface, revealing that Riku died shortly after their conversation, followed by Ryu six months later. She wonders if they have also been reborn in this world and if they are searching for her.
Life with her new family is peaceful, but Rin's unique crying and apparent understanding of their language intrigue her parents. She begins to develop rapidly, inheriting her father's agility and her mother's potential for magic. At the age of two, Rin starts attending kindergarten. There, she encounters children of various beastfolk races and learns about the world's history, including a past conflict between beastfolk and demons. She also discovers that her mother, Lyral, is half-demon, a fact that causes some prejudice from other high-ranking families.
During her kindergarten days, Rin learns about the "Picture Book Country" and its creation myth involving a "First Apostle" who created the world by turning the pages of a magical picture book. She also learns that beastfolk must touch this book periodically to prevent a buildup of magic that can be fatal.
A significant plot point emerges when Rin's father, Dan, is revealed to have been a former adventurer who investigated ruins related to the creation of demons. This leads to a confrontation with a gatekeeper named Yaargo, who blames Dan for his demotion. It is revealed that Dan, while on maternity leave, inadvertently let a thief into the Lord's mansion, who stole an item that was later gifted to Rin. This incident caused Yaargo's demotion.
Rin's mother, Lyral, is revealed to be a powerful and respected figure in Haku-san, having served the territory for a long time, even being a knight before becoming Lord Targats's advisor. This causes friction with Lord Targats's wife, Lia, who harbors prejudice against demons and Lyral.
The narrative builds towards the baptism ceremony of Lord Targats's daughter, Taria, for whom a bodyguard is being chosen. Lyral is tasked with approving the candidate, a skilled bear-person named Beates. The selection process is complicated by Lia's prejudice against Beates due to her appearance and Lyral's demon heritage. Ultimately, Targats intervenes, and Beates is appointed as Taria's bodyguard, with Lyral and Betty also accompanying them.
The chapters conclude with Rin's first day of kindergarten, filled with new encounters and the beginning of her integration into this new world, while her past life connections and the mysteries of her reincarnation continue to unfold.