721st Naval Air Group (Jinrai Butai — Thunder Gods Corps)

The 721st Naval Air Group (第七二一海軍航空隊) was established on October 1, 1944, at Hyakurihara Air Base in Ibaraki Prefecture under the command of Captain Motoharu Okamura. It was given the name Jinrai Butai (神雷部隊, Thunder Gods Corps) and tasked with deploying the Ohka rocket-powered special attack aircraft against Allied naval forces. The Ohka could not take off by itself: it was carried under a G4M "Betty" land-based attack bomber and released near the target, after which its pilot steered it into a ship.

The unit transferred to Konoike Air Base (神之池基地) in November 1944 to begin intensive training. Besides the Ohka squadron it included the bomber squadrons that flew the mother aircraft and fighter squadrons for escort. The 722nd Naval Air Group (Tatsumaki Butai / Tornado Corps) was later formed at Konoike to continue training Ohka pilots and bomber crews. In early 1945 the main body moved to Kanoya and other bases in southern Kyushu.

Operational missions were launched from Kanoya Air Base in Kagoshima Prefecture, beginning with the disastrous first sortie on March 21, 1945, led by Lieutenant Commander Goro Nonaka. Japanese accounts record 18 bombers (15 carrying Ohka) with a Zero escort; intercepted by U.S. carrier fighters, every bomber was shot down, about 160 men were killed and no Ohka was released at a target. The unit then switched to small dispersed sorties and also flew bomb-carrying Zero fighters as the Kenmu special attack squadrons. On April 12 an Ohka sank the destroyer USS Mannert L. Abele, the weapon's clearest success. Ohka operations continued through the Battle of Okinawa until June 22, 1945.

Figures for losses vary. Japanese sources give 829 dead for the group as a whole, including 55 Ohka pilots and 365 bomber crewmen; this site's earlier text gave approximately 56 Ohka pilots. Many crew members died when their mother aircraft were shot down before the Ohka could be released. The unit was disbanded in late August 1945 following Japan's surrender. Okamura took his own life in 1948. Shelters and memorials survive at the former Konoike base (now Kashima, Ibaraki) and at Kanoya.