sentences:  The Nakajima G5N "Shinzan" originated due to the Imperial Japanese Navy's interest in developing a long-range attack bomber capable of carrying heavy loads of bombs or torpedoes a minimum distance of .To meet this requirement, it became apparent a four-engine lay-out would be necessary.As Japanese aircraft manufacturers lacked experience in building such large complex aircraft, the Navy was forced to search for a suitable existing foreign-made model upon which to base the new design.