Kiichi Hasegawa took command of the CV Akagi on 25 March 1941 with the rank of captain, shortly before it was assigned to become the flagship of the First Air Fleet commanded by Admiral Chuichi Nagumo during the Japaneseinvasion of theAmerican territory of Hawaii in 1941-2. He was the senior Naval officer present at the formal surrender of the American forces, along with his army counter-part, General Tomoyuki Yamashita in February 1942. He also oversaw the execution of Ensign Kazuo Sakamaki for allowing himself to be captured.
Hasegawa was quite vocal about his conflict with the Imperial Japanese Army about how best to continue the occupation of Hawaii in the face of American submarine attacks on supply convoys. When his conflicts with Yamashita got to be too much, he informed the government that he wanted to be transferred. By May 1942, he'd been relieved of his post and replaced with Captain Tomeo Kaku.