The first few produced J2M2s were delivered to the development units in December 1942 but severe problems were encountered with the engines. Trials and improvements took almost a year and the first batch of the serial built J2M2 Model 11 was delivered to 381st Kōkūtai in December 1943. Parallel with the J2M2, production of the J2M3 Raiden Model 21 started. The first J2M3s appeared in October 1943 but deliveries to combat units started at the beginning of February 1944.

The Raiden made its combat debut in June 1944 during the Battle of the Philippine Sea. Several J2Ms operated from Guam and Saipan and a small number of aircraft were deployed to the Philippines. Later, some J2Ms were based in Japanese airfields in Korea under Genzan Ku: Genzan (Wonsan); Ranan (Nanam); Funei (Nuren); Rashin (Najin); and Konan, for defense of these areas and fighting against Soviet Naval Aviation units.

Primarily designed to defend against the Boeing B-29 Superfortress, the type was handicapped at high altitude by the lack of a turbocharger. However, its four-cannon armament supplied effective firepower and the use of dive and zoom tactics allowed it to score occasionally.

Insufficient numbers and the American switch to night bombing in March 1945 limited its effectiveness.

J2Ms took part in one of the final aerial combats of the Second World War when four Raidens, accompanied by eight Mitsubishi A6M Zeros, all belonging to the 302nd Kokutai, intercepted a formation of US Navy F6F Hellcats from the aircraft-carrier USS Yorktown (CV-10) during the morning of 15 August 1945 over the Kanto Plain. In the engagement, that took place only two hours before Japan officially announced its surrender, four Hellcats were lost along with two Raidens and two Zeros.[2]

Two captured J2Ms were U.S. Technical Air Intelligence Command (TAIC) tested using 92 octane fuel plus methanol, with the J2M2 (Jack11) achieving a speed of 655 km/h (407 mph) at 5,520 m (17,400 ft),[3] and J2M3 (Jack21) achieving a speed of 671 km/h (417 mph) at 4,980 m (16,600 ft)

https://en.wikipedia.org/wiki/Mitsubishi_J2M