Tsukuba Kaigun Kōkūtai
The aircraft of the Japanese naval air group Tsukuba (Tsukuba Kaigun Kōkūtai) are probably known to many modelers because of the distinctive "Tsu" character on their tails. This training Kōkūtai underwent several organizational changes during its service. Toward the end of the war, it formed a fighter unit for homeland defense as well as several kamikaze units.
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The aircraft of the Japanese naval air group
Tsukuba (Tsukuba Kaigun Kōkūtai) are probably
known to many modelers because of the distinctive
"Tsu" character on their tails. This training Kōkūtai
underwent several organizational changes during
its service. Toward the end of the war, it formed
a fighter unit for homeland defense as well
as several kamikaze units.
Its history began at Tomobe airfield, northwest
of Lake Kasumigaura in Ibaraki Prefecture.
In the early 1930s, the base was built on the
site of a defunct sheep farm. Various army and
naval units had previously operated from this
area. In the summer of 1934, a detachment from
the Kasumigaura Kōkūtai training unit started
operations at the new base. This detachment
conducted basic flight tests, after which successful
naval academy graduates and non-commissioned
officers were assigned to advanced training.
In December 1938, a new naval training unit,
Tsukuba Kōkūtai, was established from the
Tomobe detachment. A year later, a detachment
from Tsukuba at Hyakurihara airfield became the
Hyakurihara Kōkūtai.
In March 1944, a significant reorganization took
place involving Tsukuba Kōkūtai. Its focus shifted to
operational training on combat aircraft, and it took
over equipment from the disbanded Ōita Kōkūtai.
At the same time, it transferred its previous training
aircraft to another naval unit, Tsuiki Kōkūtai (II).
One of the many commanders of Tsukuba
Kōkūtai from July 1944 was Capt. Chujirō Nakano,
who had previously commanded Kōkūtai 201
during defensive battles in the Rabaul area.
Lt. Cdr. Yasushi Yokoyama also played a key role
in the transition to combat aircraft training, taking
over as head of training at Tsukuba Kōkūtai in July
1944.
With the introduction of single- and two-seat
Zero aircraft, the grass runway at Tomobe was
no longer adequate, and the unit relocated to
Misawa airbase. In the second half of 1944, Tsukuba
Kōkūtai also received Shiden (George II) fighters
and in November formed a fighter unit composed
of instructors. This unit first engaged the enemy
on January 9, 1945, during a B-29 bombing raid on
Tokyo, but did not shoot down any bombers.
In mid-February, the unit received 24 additional
Zero fighters and had nine operational Shiden
aircraft. Around the same time, Tsukuba Kōkūtai
pilots clashed with U.S. Navy aircraft during raids
on the Kantō region on February 16 and 17. Despite
losing 14 aircraft, the Japanese pilots claimed
11 American planes shot down during the two
days. In a similar engagement on February 25,
Tsukuba Kōkūtai lost eight aircraft but claimed five
victories. After the battle, only nine operational
fighters remained.
At the same time, Tsukuba Kōkūtai was ordered
to form a special kamikaze attack unit. Initial
training took place at Kashima Kōkūtai, and by the
end of March, eight special attack units had been
formed.
On March 30, twelve aircraft from Tsukuba
Kōkūtai were detached and moved to Izumi airbase.
Their mission was to provide air cover for the
battleship Yamato during Operation Ten-Ichi Go,
a one-way voyage to Okinawa on April 6 and 7, 1945.
Japanese planes were deployed for conventional
and kamikaze attacks against Allied vessels
pursuing Yamato. Among the ships hit were the
aircraft carrier USS Hancock, the battleship
USS Maryland, and the destroyer USS Bennett,
which was heavily damaged.
Simultaneously, the Kikusui I kamikaze
campaign against ships around Okinawa began.
On its first day, April 6, a special attack unit
from Tsukuba Kōkūtai participated in kamikaze
attacks. By June 1945, another seven kamikaze
units formed from Tsukuba Kōkūtai were deployed.
From early May, Shiden aircraft began escorting
these missions, increasing the Tsukuba Kōkūtai’s
strength to 96 aircraft.
At the end of May, Shiden pilots managed to
shoot down two B-29 bombers. During June, they
also engaged long-range Mustang fighters over
the Kantō area. In the final weeks of the war,
Tsukuba Kōkūtai was relocated to Katori airbase in
preparation for an anticipated enemy invasion.
After the war, the three-story concrete building
of the former Tsukuba Kōkūtai headquarters at the
disbanded Tomobe base was used as a school and
later as an administrative building for a hospital.
In 2011, during hospital expansion and trans-
formation into a mental health facility, space was
freed up for a room dedicated to the history of
Tsukuba Kōkūtai. In 2013, demolition of the original
headquarters building was planned, but the same
year a museum of the unit was instead established
inside. In 2018, the museum moved to a neighboring
building, and the original headquarters was
declared a protected cultural monument by the city
of Kasama. The exhibition, which commemorates
the history of the base and Tsukuba Kōkūtai,
includes a replica of a Zero fighter aircraft.
Text: Jan Bobek
Illustration: Piotr Forkasiewicz
Tsukuba Kaigun Kōkūtai
INFO Eduard28
July 2025