Link here as well:In April 1943, as a private venture, Nakajima initiated studies for an aircraft (Project Z) capable of carrying out bombing operations against the US mainland from bases in Japan. Later during that year these studies served as the basis for a joint Navy-Army project, which initially was intended to be powered by six 5,000 hp Nakajima Ha-505 thirty-six cylinder radials. However, because of expected late availability of these powerplants, the design was scaled down to use six 2,500 hp Nakajima NK11A radials. In this form the G10N1 Fugaku (Mount Fugi) was designed to cruise at altitudes in excess of 32,810 ft (10,000 m) and to reach a top speed of 423 mph (680 km/h). It remained in development at war's end and never saw operational service.
http://forum.axishistory.com/viewtopic.php?t=27576
From: http://rareaircraf1.greyfalcon.us/JAPAN.htm