Secret and special weapons in Showa Japan This article refers to plans for the incorporation and development of special or secret weapon s in Imperial Japan during the first part of the Showa era , for the Second Sino - Japanese war and World War II , that were originally hidden from public knowledge to protect their efficacy . Weapons prohibited by the Geneva Protocol were of specific interest to Japan , since it was thought that if a weapon was banned then it must be particularly effective . The United States and Germany are more famous for their development of special weapons , but Japan and Russia to a lesser extent both pursued weapons development . The weapons developed by Japan included biological , chemical , and advanced conventional weapons . A diverse cross section of institutions and individuals in wartime Japan participated in various areas of development , such as The Munitions Ministry ( Japan ) , the Tokyo Imperial University , the " Riken " ( Japanese Institute of Physics and Chemical Research ) , the Black Dragon Society , the Mitsubishi business conglomerate , and the Nakajima Company . Military units involved included the " Kempeitai " , First Tachikawa Army Arsenal , Sagami Army Arsenal , and Yokosuka Naval Arsenal . Japanese army interests in development of secret weapons . With the reinforcement of the defenses of the homeland , a strong desire arose within Imperial General Headquarters to improve the military situation by the invention of Special or Secret weapons for decisive combat . In order to apply science to military problems , from every aspect , IGHQ therefore appealed to scholars and technical experts for their co - operation . Among the various assorted types of such weapons intended for decisive battle , the Japanese Army made efforts to put infra - red radiation to practical use . They tried to perfect heat - seeking bombs , in order to sink American troopships , with a 100 % certainty of kill . This was expected to retrieve Japan ' s fortunes in one fell swoop . In mid - 1944 , experimentation with these projectiles was carried out near Lake Hamana , in co - operation with many scholars and technicians . Difficult problems appeared in succession , however , requiring resolution , and the bombs could not be put to practical use . Other secret weapons were evaluated with similar results . Since the war situation was coming to a head before the completion of thermal - ray weapons , IGHQ was obliged to rely upon ramming techniques : Suicide ships or " special - attack " planes which could be easily produced in large numbers . Weapons for decisive combat thus came to mean suicidal expedients . Another project — this one slightly more successful — was the Fire balloon ( " fūsen bakudan " ) , a paper - enveloped hydrogen balloon carrying a small bomb , which actually could reach the United States by taking advantage of the jet stream , which the Japanese were the first to discover . For six months starting in November 1944 , the Japanese Army ' s Special Balloon Regiment released balloons ( totaling some 9 , 000 ) . The object was not necessarily to inflict casualties but to damage morale in the U . S . . In practice little damage was caused , only six people killed and forest fires started . The Japanese were convinced the campaign did no damage due to the suppression of news of the balloons . At Japanese Army schools , the students were not very well trained in science and technology . Infantry remained the backbone of the Japanese Army , as in olden days . Spiritual strength was considered to be the primary element in the acquisition of victory . With the deterioration in the war situation , there was a growing desire within military circles to perfect miraculously effective weapons . Nevertheless , it became abundantly clear that the low scientific level of the nation could not possibly yield elaborate weapons . Thus , during the course of the war , the gap between the Japanese and the American scientific potential for national defense grew ever wider with the passage of time . Weaknesses in national science were certainly a major factor in Japan ' s loss of the war , but poorness and neglect of science were not attributable to the Japanese Army alone . It may well have been because the Japanese adopted principles of makeshift expediency ever since the Meiji era . The Japanese Army ' s attitude toward technology incurred many kinds of great criticism from private sources at the time , the major points being the following : Mass destruction weapons . The Japanese investigated nuclear weapons but progressed no further than laboratory experiments . Chemical and biological weapons research was carried out by Unit 731 , Unit 100 , Unit 516 and other similar sections . Some of the unit commanders were prosecuted for war crimes , while others , such as Unit 731 , were granted immunity from prosecution in exchange for sharing biological warfare secrets with the American military . Advanced aircraft and missiles . This section analyzes some advanced types of Army and Navy aircraft : Advanced tanks and armour equipment and captured armors . Armoured fighting vehicles under development before the end of the war .