Nambu pistol is probably the best sidearm used by japan during World War 2. It uses a bottlenecked 8mm cartrige, a needless complication for a round which had ballistics roughly equal to .380ACP. Its trigger-guard has been enlarged from previous models to permit operation while wearing gloves. An unremarkable weapon of mediocre reliability, it explains why many Japanese officers preferred swords to handguns for close-range combat. Other handguns in Japanese service were even worse. You will find a good technical description of this and similar models at Max Popenker's site.