The character Shikishima (played by Ryunosuke Kamiki) carries a heavy burden of regret; he was a kamikaze pilot who avoided death during the final days of World War II by claiming his aircraft malfunctioned. With Japan now defeated and in ruins, he experiences profound shame. He secures employment on a boat tasked with clearing mines from the sea, and it’s during this work that they encounter a dangerous creature spawned from the aftermath of the atom bomb. This being seems intent on destruction, proving impervious to conventional weaponry, even possessing a powerful blue beam capable of complete annihilation. As it moves toward land, causing widespread damage, scientists scramble to devise a solution before the nation is destroyed. The film essentially weaves together two narratives: one focusing on Shikishima’s personal struggles—his guilt, his developing relationship with a homeless woman and her child, and his growing sense of hope—and the other being a more conventional spectacle featuring special effects reminiscent of "Godzilla." I personally found this style preferable to contemporary Hollywood versions. The animation has a rougher quality, the monster appears more menacing, and the setting in post-war Japan creates a visually striking and desolate atmosphere. While the conclusion is foreseeable, the filmmakers attempt a somewhat inventive approach to resolving the threat posed by this destructive creature. It doesn’t break much new ground, but I still found it enjoyable.

Source on TMDB