One day, after the funeral of his grandmother, Matsuno, he is startled to learn from his mother and older sister Keiko that his maternal grandfather Kenichiro was not his blood-relation.

Keiko and Kentaro start hearing stories about their real grandfather, Kyuzo Miyabe and visit many of his former comrades, all of whom begin by criticizing his "timidity" in battle.

During conversation with an old comrade of his grandfather, Izaki, who is in hospital dying of cancer, Kentaro finally learns the reason why Miyabe became a kamikaze pilot.

Izaki talks about his relationship with their grandfather to Keiko and Kentaro, claiming that only the "timid" Miyabe gave him the hope to save his own life after he was shot down over the ocean.

Kyuzo Miyabe, the pilot of the Zero, is regarded by his comrades as a coward, though an exceptionally skilled fighter pilot, for consistently returning alive from missions, openly explaining "I don't want to die," the result of a promise made to his wife Matsuno and daughter Kiyoko to return from the war alive.

At a blind dinner date with several friends, he becomes incensed when one compares the kamikaze pilots to suicide bombers and storms off.

One summer day in 1945, Kyuzo Miyabe boards a Zero fighter, but then asks Kenichiro if he can "make a selfish request" and change planes with him.

Kenichiro's plane develops engine trouble, and he has to return, leaving Miyabe alone to attack an Essex-class aircraft carrier.

"[5] The film uses computer-generated imagery to replicate the scenes of bombing runs and dogfights, given the limitation of having a small number of Zero fighters being in a flyable condition having survived till the present day.

[12][13] The Eternal Zero won the Golden Mulberry, the top audience award, at the 16th Udine Far East Film Festival in Italy.

[citation needed] The film received 8 prizes at the 38th Japan Academy Awards: The Eternal Zero has come under criticism for its nationalistic and sympathetic depiction of the Kamikaze pilots.

[16] Director Hayao Miyazaki in an interview accused the film of "trying to make a Zero fighter story based on a fictional war account that is a pack of lies".