One war movie is such a "masterpiece" it received a perfect 100% on Rotten Tomatoes, ranked as the top war film on its site, and was hailed the "best war movie ever". Now streaming on Netflix, the 1988 animated tale isn't what you'd expect from a war film, but critics say the tragic and heart-wrenching storytelling evokes deeper and more complex emotions.

Set in the final months of World War II, Grave of the Fireflies follows teenage Seita and his younger sister Setsuko as they try to survive in the rubble of firebombed Kobe, Japan, after losing their mother. Directed by Isao Takahata, the devastating scenes are infused with emotional rawness, inspired by Takahata's own experiences of war, which he described as “the defining event of my life.”

In 1945, Isao and his older sister had to flee their home barefoot after incendiary weapons set their house and city alight in Okayama, western Japan. But in the chaos of the attack, the siblings had run the opposite way from their family.

While wandering the streets alone, his sister's clothes set alight, leaving her scarred but alive, and she often attributed her younger brother as the only reason she lived as he beat out the flames.

The quiet and restrained animation narrates this weight of children's suffering in war, showing a world where their laughter dims under hunger, and the vulnerable are not protected.

Some 47 professional critics gave the film a stellar 100% rating on Rotten Tomatoes, while more than 10,000 audience ratings averaged at the near-impossible score of 95%.

One professional critic wrote: "Grave of the Fireflies is simply a work of art; a film that, more than thirty-five years ago, demonstrated that animation can be used to tell mature, bloody, emotional, tragic, believable and very human stories."

Another critic hailed: "It is not difficult to attribute the word masterpiece to one of the best films ever made about war."

A third wrote: "Some movies are such singular achievements that they deserve to be seen at least once by everyone who considers himself or herself to be a lover of film. Grave of the Fireflies falls into that exclusive category."

Meanwhile, the Telegraph said the film is a "masterpiece" and "the most devastating war film ever made."