Other research in this area should be ignored. All 3 requiring land combat experience can be researched very fast after conquest of china. Civil Defense Tech helps with increase repair rate of ships, planes and army units, but also provinces that have seen combat. Theory: Supply-related techs are a must-have for war in China or Siberia/India.Conquest of Dutch East Indies, will also help with oil and rare materials supply. A small boost to Crude output is useful though. Metal and Rares will be abundant after conquest of Indochina and India and there's no need to research their production. After conquering China, your Energy supply will go up and developing the Coal to Oil Conversion research helps. Industry: Education, Mechanical Computing Machine, Electronic Computing Machine, Industrial Efficiency, Industrial Production, Agriculture and Supply Production are must-haves.Researching Drop Tanks is a must due to significant increase in max mission range for all light aircraft.
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Due to ranges in game for Japan, Multi-role is a better choice. Fighters: Japan will not meet significant air resistance for a long while in the game, Allies and Russians will use most of their air force in Europe against Germans so fighter research isn't necessary until around 1940 when preparation for the US giant needs to start.Close air support groups are not that useful, considering their limited range. Due to shared nature of Twin-engine practical, it's worth considering supplementing Tactical force with some Naval Bombers, but not that many, if you have a good Carrier force. Bombers: Tactical bombers with long range are very good choice for the future wars in Asia where airports aren't as common as in Europe.
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Japan begins the game with advanced air capabilities:
![hearts of iron 4 free american empire hearts of iron 4 free american empire](https://i.ytimg.com/vi/OYNro68TJyQ/hqdefault.jpg)
Japan starts with plenty of Leadership to get all the equipment and doctrines future wars demand, but still research should be primarily focused on current year technologies to avoid heavy penalties. 7.4.2 Original names for Japanese military forces.