The inspiration for this film comes from a book of letters. When Eastwood was preparing for "Flags of Fathers", he had a keen interest in the Japanese commander Kuribayashi Tadao in the Battle of Iwo Jima. Kuribayashi ordered a large number of caves and tunnels to be excavated on the island to ambush military forces. This tactic is simply "heresy." At that time, Japanese troops in defensive battles would often lay out their lines of defense at the landing point and concentrate their artillery fire on the enemy at sea. However, relying on Kuribayashi's peculiar strategy, the battle that the US military thought would be over in 5 days dragged on for 36 days. In addition, the Japanese Army Lieutenant General once went to the United States and Canada to study. He has many American friends and has always opposed war with the United States. However, he showed a resolute attitude in the battle of Iwo Jima. Eastwood kept digging through Lilin's materials and found the book "Letter from Commander-in-Chief Jade Fragment". The book contains letters sent by Kuribayashi to his family during his stay in the United States. Interesting pictures can be seen everywhere in the letter. The military attache’s affection for his wife and children was vividly on the paper, which greatly moved Shen Eastwood, so the "letter" became The key words of the film.
Kazu Ninomiya, a member of the popular idol group "Arashi", also has a place in the film. The soldier Saigo played by him is a key figure throughout the battle. Although the young Ninomiya is mainly active in the singing world, he has also appeared in many TV dramas and stage plays and has considerable experience in acting.
