Hirao Kaiten Base opened in March 1945 as the Japanese Navy's third kaiten
training base after Otsushima and Hikari, also located in Yamaguchi Prefecture.
Nine kaiten pilots from Hirao died during WWII, and this monument erected in
1959 honors these men. A sign in front of the monument summarizes the history of
the kaiten base and monument:
Special Attack Corps
Human Torpedo Kaiten Monument
In March 1945 when the buds on the cherry trees were swelling, a kaiten
sortie and training base was established here at the tip of Atata Peninsula.
At the base petty officers not even 18 years of age and youthful officers in
their early twenties sacrificed themselves and devoted their time to
rigorous training day and night in order to protect their country.
The word "kaiten" has the meaning of "restore power of waning country."
This kaiten special attack weapon, also called a "human torpedo," had a
length of 15 meters, a diameter of 1 meter, and a speed of 30 knots or 56
km/hour. It was designed based on the Type 93 torpedo, considered to be
world-class in those days. The front tip was filled with 1.55 tons of explosives,
and one pilot rode in a seat in the middle section. It was called a
"sure-death" weapon as he rammed the kaiten into an enemy ship while
For training in the beginning stages, there were round trips around Hirao
Bay. Later they left the waters of Zoshiseto and made crossings between the
three small islands of Ushima, Umashima, and Kanoushima. They had rigorous
training in which they practiced attacks against moving ships at dawn or
dusk. They usually carried these out while submerged, but at times they
surfaced and hit a target ship while making visual observations through a
On July 18, 1945, Submarine I-58, carrying six kaiten, left from Hirao
Base. Five young men gave their lives in kaiten attacks in Okinawan waters.
In addition, three kaiten crewmen died during rigorous training at Hirao,
and one person took his own life soon after the end of the war.
In August 1945 came the end of the tragic war that had taken the precious
lives of these youths who had great promise. Soon Japan miraculously
recovered its national strength and started to enjoy peace. This was a gift
based on the noble sacrifices of all of those men who went before. Here at
Atata we again offer up our true thanks, and we solemnly pray for the souls
of those for whom Atata was the final place of their lives.
In July 1959, this monument was erected here to pass down to future
generations the importance of peace. This kaiten monument was erected
through the cooperation of Kouji Tani, factory manager at Matsukura Kaiji
Corp., and placed on the company's land. Afterward, the monument was
maintained with care by persons associated with Matsukura Kaiji Corp. and
Hirao Kogyo Corp. Now due to repair work of the Hirao Bay harbor, there was
no choice but to move it. In November 2004, the monument was restored and
moved here through donations from the Hirao Kaiten Association and with the
cooperation of various persons related to the kaiten monument.
The Hirao Branch of the Otake Submarine School also had a training base,
adjacent to the kaiten base, that was principally used for Koryu and
Kairyu special submarines.
Hirao Town Tourism Association
A bronze kaiten replica lies in a bed of gravel in front of the monument. In
front of this replica, the right-hand plaque has engraved the five names of the
I-58 kaiten pilots from Hirao who died in battle, and the left-hand plaque has the names of
the three men who died in training and the one man who took his life when the
end of the war was announced.