Part fantasy, part mystery, this young adult novel belongs to a subgenre of stories about getting literally “sucked into” a book, with a couple key distinguishing traits. First, instead of the protagonist going into the story, the story consumes reality, changing Yomunaga and its residents into the book's world and characters. Second, our protagonist Mifuyu Mikura is a reluctant heroine who adamantly hates reading books.

As a bookworm myself, it's a testament to Fukamidori's character writing that I wound up loving “book-hater” Mifuyu. She's written with sympathetic, sometimes humorous realism: a quarrelsome, impulsive, lonely 15-year-old whose words don't always align with her actions or thoughts. She's often apologizing for losing her temper or making thoughtless remarks, yet she's also proactive and reliable under pressure, moving decisively where others hesitate. The contrast makes her an effective hero, pushing the story forward even as she gripes about it.

Her attitude starts to make sense as the story teases out Mifuyu's family history and the burden—both socially and financially—of the Mikura legacy. Mikura Hall hangs like a weight around Mifuyu's neck, as does the memory of her “stern, unforgiving” grandmother obsessed with protecting their book collection to the exclusion of everything else. Feeling isolated from the rest of the town and relatives, it's easy to see why Mifuyu feels trapped by her lineage and despises the books that symbolize her family's legacy.

Yet despite Mifuyu's reluctance, she finds herself invested in the fantastical book worlds that take over the town, thanks in large part to the arrival of the shapeshifting dog-girl Mashiro. Their relationship forms the crux of the first half of the novel, which follows an episodic, cyclical structure as Mifuyu and Mashiro explore three action-packed novels in their pursuit of a thief. Mashiro serves as the loyal animal helper who rescues Mifuyu from danger, but more importantly, she becomes the first friend Mifuyu can trust with her troubles.

Thanks to Mashiro and their adventures, Mifuyu grows more curious about the world, people, and books around her. This personal shift coincides with a structural story shift, as the back half of Whoever Steals This Book breaks the episodic cycle and concerns itself with uncovering broader mysteries about the Mikura family and the source of the book curse.

Mifuyu's relatives become integral to the story, especially her dad and grandmother. Although deceased, Mifuyu's grandmother looms large, realistically terrifying as the selfish, strict older relative forcing their rigid ideals on younger generations. Her mundane malice helps ground a fantastical story in genuine feeling and trauma, creating a strong throughline for the entire family.

Whoever Steals This Book makes for an engaging character-driven mystery, especially in how it gradually ties Mifuyu's story to her older relatives and adds a layer of complexity to the earlier, lighter adventures. Admittedly, the “culprits” for the thefts have pretty thin motivations and personalities. They mostly exist as plot devices so the author can insert a bit of moralizing about shoplifting. It's clunky but easy to scoot past in favor of the central story. The final reveal and climax tie themselves much more neatly into the novel's subtler themes of loneliness, trust, exploitation, and the importance of sharing one's stories with others.

As a book about books that jump in and out of genres, the prose itself is essential to establishing the tone and setting of each book world, with mixed results. When Mifuyu reads from the books, the writing style shifts to match. The “magical realism” story has a poetic rhythm to it, while the “hard-boiled” noir is grimy and blunt, with tongue-in-cheek lines like “I'm no stranger to dancing with the devil.” Sadly, these stylistic shifts mostly fall away when Mifuyu stops reading the story and starts interacting with it which feels like a missed opportunity to play with format and fully depict the book's takeover of the town.

Overall, the writing is solid, fluctuating between “workmanlike” at worst and “riveting” at best. It's easy to follow throughout—a bit plodding when establishing Yomunaga in the early scenes but finds its rhythm once the first book curse activates. Like a lot of pop fiction, it sometimes seems like the author doesn't trust the reader to fill in gaps or connect dots, so there are periodic issues with repetitive summaries, unnecessary details, or stiff descriptions that read more like book reports than creative writing.

Fortunately, most of the novel is either colorful dialogue or action scenes that flow with page-turning ease. Fukamidori has a knack for clearly depicting rapid-fire events while still building tension and uncertainty, and her most evocative descriptions occur within the flow of the adventure. I struggled to start this one, and suddenly I couldn't put it down.

Whoever Steals This Book blends genre-hopping fantasy with an intriguing family mystery to create an entertaining, imaginative read that also manages to wield emotional heft and substance. Despite a slow start, some structural weaknesses, and a touch of moralizing, I found myself endeared to the cast, caught up in the adventure, satisfied by the ending, and still mulling over how later details changed my interpretation of earlier events. That makes it a worthwhile read in my book, especially for fellow bookworms or YA fantasy fans.