Short answers, pulled from the story.
The Imperial Japanese Army began its formation in March 1869 when the imperial government created various administrative offices including a new military branch. This unit consisted of Satsuma and Chōshū troops strengthened by veterans from the battle at Toba, Fushimi.
Universal conscription for all male subjects in Japan was enacted on the 10th of January 1873 through the conscription ordinance. The law required seven years of total military service divided into three parts with active duty followed by reserve periods.
By 1945 there existed 6 million soldiers within the Imperial Japanese Army ranks totaling 6,095,000 personnel including 676,863 Army Air Service members. These forces suffered severe shortages of supplies including food medicine munitions and armaments from 1943 onwards.
The Nanjing Massacre stands as the most well-known example among these crimes committed by the Imperial Japanese Army alongside rape forced prostitution death marches and biological warfare programs targeting civilians directly. Execution of prisoners became standard practice throughout conflict zones causing tens of millions of deaths across Asia and Pacific regions.
Intelligence officer Hiroo Onoda surrendered on Lubang Island in Philippines in March 1974 while Teruo Nakamura surrendered later on Morotai island December 1974 appearing final holdouts though reports exist other Japanese stragglers surrendering after date.