Japanese night-fighter. There is an excellent book on this airplane, #8 in the "Famous Aircraft of the National Air and Space Museum" series. Its title is Moonlight Interceptor - Japan's "Irving" Night Fighter by Robert Mikesh. It has lots of general information on the type, as well as chapters devoted to the restoration of the Museum's example from 1979-1983 (17,247 man-hours!) The entire series is excellent, I would recommend any of them. I also have #3 on the P-80 and #9 on the Fw 190F-8.
In 1938, before Zero had flown, Navy issued spec for 2-engined, long-range escort fighter to reach speed of 280 kts and range of 1300 nm (2000 nm with extra fuel). Mitsubishi abandoned project, but Nakajima design team succeeded in producing large prototype which proved to have remarkable maneuverability. Fitted with large fabric-covered ailerons, slotted flaps (opened 15 for combat) and leading edge slats, could dogfight well with Zero; prototype eventually developed with no flight limitations. But Navy doubted practicality of complex scheme of 2 dorsal barbettes each mounting 2 7.7 mm guns remotely aimed in unison by navigator. Eventually, Navy decided to buy J1N1-C, with barbettes removed, as 3-seat photographic aircraft. (Some reports claimed failure as fighter due to lateral control problems, but test pilots insist it was simply lack of suitable armament). Soon after sorties began over Solomons spring 43, commander of 251st Air Corps hit on a way of intercepting Allied heavy night bombers. Had several aircraft modified as C- Kai night fighters with upper and lower pairs of oblique-firing cannon. Armament proved effective, and most J1Ns built as fighters with nose radar and smoother cabin outline. Were good, robust aircraft but unable to intercept fast, high-flying B-29. (Earlier, Germans had mounted 2 20 mm fixed guns underneath Ju 88C-6 aimed to fire obliquely upward and forward; called "Schraege Musik" mounting which translates roughly as jazz (American, that is. Worked well, especially at night; it took a while for RAF to figure out what was happening to their bombers. The Germans also used this gun mounting on the Bf 110 and other night fighters)