Go Nagai crossover movie.

As World War II reaches its conclusion in 1945, Japan faces widespread destruction in the form of American bombings, devastating city after city. Hotaru no Haka, also known as Grave of the Fireflies, is the story of Seita and his sister Setsuko, two Japanese children whose lives are ravaged by the brutal war. They have lost their mother, their father, their home, and the prospect of a bright future—all tragic consequences of the war. Now orphaned and homeless, Seita and Setsuko have no choice but to drift across the countryside, beset by starvation and disease. Met with the apathy of adults along the way, they find that desperate circumstances can turn even the kindest of people cruel yet their youthful hope shines brightly in the face of unrelenting hardship, preventing the siblings from swiftly succumbing to an inevitable fate.

Go Nagai crossover movie.

A year has passed since the events of SSSS.Gridman. The world is at peace and no one except for Rikka and Utsumi remembers the kaiju, Gridman, or Akane Shinjou. This includes Yuuta, who despite serving as Gridman's host, has no memory of the most important moments of his life. So when a new Kaiju appears, he leaps at the chance to prove to himself that he too can be the hero by merging with Gridman once more. (Source: ANN)