He was a Nisei, which means that he was a second generation Japanese-American. Otani"s family was interned at the Gila River War Relocation Center in Arizona Otani joined the United States Army in 1943. He volunteered to be part of the all-Nisei 442nd Regimental Combat Team.
This army unit was mostly made up of Japanese Americans from Hawaii and the mainland.
On July 15, 1944, Otani was serving as a staff sergeant in Company G of the all volunteer Japanese American 442nd Regimental Combat Team. On that day, near Pieve di Santa Luce, Italy, his platoon became pinned down in a field by an enemy machine gun and snipers.
After killing one sniper, Otani shouted directions to his platoon and repeatedly exposed himself to the hostile fire, creating a distraction which allowed some of his men to reach cover. He then crawled to a wounded soldier who was lying in an exposed position and began rendering medical aid, but was killed by enemy fire in the process.
Otani, aged 26 at his death, was buried in Veterans Liberty Cemetery, Fresno, California.
In the 1990s, there was a review of service records of Asian Americans who received the Distinguished Service Cross during World World War World War II In a ceremony at the White House on June 21, 2000, his family was presented with his medal by President Bill Clinton.