For decades, literature lovers have fretted that some classics have been obscured by their animated film adaptations, which youngsters might see as definitive. How many people, for instance, now think of Alice's Adventures in Wonderland, Bambi and The Jungle Book as being films by Disney, rather than books by Lewis Carroll, Felix Salten and Rudyard Kipling?

I had similar thoughts reading the new translation of Grave of the Fireflies, the award-winning Japanese novella by Akiyuki Nosaka, about the lives and deaths of two children at the end of World War II. (This isn't a spoiler; their deaths are revealed in the opening pages.) It may still be a set text at some Japanese schools, especially given its brevity - the translated edition is barely sixty pages long. However, I'm also guessing more Japanese youngsters know Fireflies through Isao Takahata's Ghibli film, pictured right. If they know it at all, that is. A Japan Times article this summer quoted a university professor who said hardly any of his students had seen it.

In Anglophone countries, on the other hand, most of the people who'll read this translation will come to it from the film, which is still one of the most critically acclaimed anime ever. It's not just heartbreakingly sad. It's immensely powerful, with moments and images that'll stay with you even if you follow the cliché and only ever watch it once. Moreover, the anime is extremely faithful to Nosaka's story; there are few major differences, and many are additions on the film's part.

As someone who's seen Takahata's film many times, I can't judge the book purely on its own merits. The film is “overlaid” on every page, and often on individual paragraphs and lines. However, that's not at all to say that the book doesn't have a distinctive texture. Here's a fairly typical sentence from early in the story, where the young boy Seita, the book's viewpoint character, looks up to see the American bombers over his home city of Kobe.

Until then, he had only seen them as barely discernible dots headed east leaving vapor trails, and during an air raid on Osaka just five days before weaving through the clouds over Osaka Bay like a shoal of fish, but now they were right overhead, huge, and so close he could even make out the thick line painted on the underbelly as they headed from the sea to the mountains then abruptly tilted their wings and disappeared westwards, and then once again the sound of bombs falling and he stood petrified as if the air had abruptly become too dense to move in, there was a clatter as something blue fell from the roof, an incendiary 12 bomb five centimeters wide and sixty centimeters long went bouncing up and down the road like an inchworm spraying oil.

The book's translator is Ginny Tapley Takemori, who also translated Murata Sayaka's bestseller Convenience Store Women and a novella based on Makoto Shinkai's She and Her Cat (which I reviewed elsewhere). She discusses Grave's prose style in a very useful afterword. Nosaka, she explains, actually uses longer run-on sentences in the Japanese text, with fewer stops, to convey Seita's stream of consciousness. However, to make the book more accessible, Takemori decided to break up the sentences, “while attempting to maintain the breathlessness and confusion of the original.”

I thought it worked extremely well, but then I had the “advantage” of having Takahata's film play in my head as I read. Of course, the style lends itself to depicting the sudden associations and wanderings of Seita's mind, especially the intrusion of happier memories from before the bombing, now infected with anguished sadness. That experience has recent resonances in animation. We've seen how Ghibli would animate the story, but imagine Pixar daring to adapt it as a bleak Inside Out film.

Seita and his toddler sister Setsuko, who's only four, eventually end up living on their own in a tunnel shelter. Their “escape” from grown-up society is the story's turning point - a terrible turning point, as we'll see by the end, but that's not obvious, at first. The siblings collect fireflies to light their new home, and Seita is once more immersed in memories, lyrically so. This time, his memories are of a naval review featuring his beloved father, who'll surely save them in the end. Even as a dropout, Seita hungers for patriotism and patriarchy.

But soon, hunger is all he and Setsuko know. It becomes impossible to find food, and Seita can only remember the sweets and treats and feasts he enjoyed when he was younger, how there was once a time when he actually turned food down. Now, he imagines cutting a finger off to feed his starving sister: “One finger wouldn't matter. She could eat the flesh off it.” There is no hope for them. Nosaka has already told us how their story ends.

The hunger is conveyed more strongly in the prose than in the film, or at least with a different strength. It's horrible to watch images of malnourished children on screen, but the prose conveys the obsessions of a desperately hungry child. Even in the first pages, we get a long list of all the foods on offer at a black market, if only you could afford them: “steamed sweet potatoes, sweet potato dumplings, rice balls, bean jam rice cakes, fried rice, bean soup, bean jam buns, udon noodles…

The book also has a frankness about some details that the film doesn't reach, though Takahata gestures at them. Excretion is a motif – the book has a comic anecdote about a very young Setsuko swallowing a marble, and how the family got it back, placed among ghastly and mortifying moments as the children's bodies fail. There are references to Seita's nascent sexuality, and the feelings he sometimes has for his mother and occasionally even his sister, though he's no abuser. (It's hinted in Takahata's film, though so briefly it's easily missed.)

The film also brings a great deal to the story – most fundamentally, far more of a presence for Setsuko. In the book, she's ghostly. For instance, the sequence where Seita flees through the burning city of Kobe is powerful, but it's all through the boy's eyes. Setsuko's reactions aren't mentioned at all, even though she's strapped to Seita's back. She does get dialogue, and there are moments of heartbreak, as when she tries comforting Seita like a grown-up after he's taken a beating. We get a sense of her, both as a real child and the angelic figure who Seita sometimes sees.

But Setsuko is far more present in the film version. One factor is Takahata's bold decision to have her voiced in Japanese by a real toddler, Ayano Shiraishi. The film also has numerous moments centered on her that aren't in the book. A key example is a scene outside Seita's school; Setsuko starts crying because she can't see her mother, while Seita vainly tries to distract her by flipping over a horizontal bar. In the book, Seita's action is mentioned, but without Setsuko's reaction, it's barely a scene at all.

There's a similar kind of difference when Seita is told to sell his mother's kimono for rice. In the book, he obeys without issue, whereas in the film, Setsuko throws a tantrum that's hard to watch. Reading the book through the film, there are many such startling “omissions,” such as the strand with the candy tin. In Nosaka's story, it's mentioned once, whereas in the film, it's Setsuko's beloved possession that encapsulates the story's trajectory, a vessel first for sweets, then for cremated bones.

Then there's the film's most joyous moment, when Seita capers through a field at night amid fireflies. Even this is not in the original story. For me, that was like reading the original Sound! Euphonium light novel and realizing it didn't have the ”running over the bridge” scene from Kyoto Animation's TV version. In both cases, it's such a peak in the anime that it's almost impossible not to see the source book as “wrong” for omitting it. Good books can be damaged by bad film adaptations. Grave of the Fireflies shows how an appreciation of a good book can be hampered by an outstanding adaptation.

The most prominent difference between the book and the film is that the latter adds the device of Seita's ghost as our guide, reliving his story as it plays out. In the book, there's no suggestion of the supernatural except as the mortal Seita perceives it. And yet, intriguingly, Takemori notes in her afterword that wasn't the case in Nosaka's first draft. That had a final image that might be dismissed as Disneyesque sentimentality… before you remember the whole story was written as Nosaka's memorial for his real adopted sister. She died at the age of sixteen months, just as World War II ended.

”That night, countless fireflies flew up from Nunobiki valley and formed a single stream that flowed down into the thicket of weeds outside the bayside exit of Sannomiya Station, covering the area where Setsuko's bones had been thrown away as though to protect and comfort her, comfort her.”