Naru Kotoishi is a young girl around six or seven years old who lives in the Goto Islands with her grandfather, Kousaku Kotoishi. Her father is Yuuichirou Kotoishi, and little is clearly known about her mother; there are only unconfirmed rumors among the islanders. She is a first-grade student and a central figure in the life of calligrapher Seishuu Handa after he moves to the island.

Naru has a cheerful, hyperactive, and endlessly curious personality. She is impulsive and often acts before thinking, which leads to mischief and moments of disobedience toward Handa and other adults. She is a tomboy who enjoys playing outdoors, collecting bugs and shells from the beach, and exploring the island with her many friends. Her boundless energy can overwhelm Handa, especially when he is trying to concentrate on his work, but she also demonstrates a genuine warmth and earnest desire to include others in her activities. The local dialect term barakamon, meaning energetic or cheerful child, directly reflects her nature, and her joyful, self-introducing exclamation of her own name is one of her trademarks.

Her primary motivation is simply to have fun and share that joy with everyone around her. She does not have any supernatural abilities or special talents; her greatest strength lies in her ability to connect people and foster a sense of community. She shows deep empathy and an intuitive understanding of others' feelings, and she consistently tries to cheer up Handa when he is down, even if her methods are sometimes clumsy. This social instinct makes her a natural bridge between Handa and the close-knit island community.

In the story, Naru serves as both a source of chaos and a catalyst for Handa's personal and artistic growth. Her persistent, friendly intrusions force Handa to let go of his rigid, city-bred expectations and embrace the slower, more spontaneous rhythm of island life. Although she initially frustrates him, she gradually becomes his closest companion and a key source of inspiration for his calligraphy. Her innocent, unpretentious outlook helps Handa see the beauty in simple, everyday moments, guiding him toward a more authentic artistic style.

Her relationship with Handa is the heart of the narrative. It begins with Handa feeling overwhelmed by her energy, but over time they develop a deep, familial bond. She often visits his house without invitation, treats it as a second home, and looks to him as both a playmate and a mentor. Handa, in turn, learns to protect and care for her in ways that also teach him responsibility. Naru also maintains a close relationship with her grandfather, who provides her a stable home. Among her peers, she is an inclusive and outgoing friend to other island children, often leading them in games and adventures.

Naru shows meaningful development throughout the series. Early on, she is purely a force of playful chaos, but she gradually learns to understand boundaries and the importance of apologizing when her actions go too far. Her growing awareness of Handa's struggles and her own role in helping him demonstrates a budding maturity. At the same time, she remains true to her spirited, curious nature, embodying the lesson that growth does not require losing one's childlike wonder. She participates enthusiastically in local festivals and community events, highlighting her connection to island traditions and her role as a unifying presence.