With the start of the Pacific War in 1941, Ichiki was promoted to colonel and was placed in command of the IJA 28th Infantry Regiment, from the 7th Division, which consisted of 3,000 troops, and was assigned to assault and occupy Midway island.
Ved starten af Stillehavskrigen i 1941 blev Ichiki forfremmet til oberst og blev chef for det 28. infanteriregiment i 7. division, som bestod af 3.000 tropper og som skulle angribe og besætte Midway.