Decisive Battle! Maidens' Battlefield 3 ~ Lightning Strategy! The Results Are

This is the story of a world set about half a century after a Second World War that differed from real history.
After the world war, a certain nation that had temporarily led the world as the center of the victorious powers suffered a massive explosion due to the failure of a major scientific experiment, reducing nearly all of its territory to scorched earth.
With the destruction of this nation, the global military balance that had been maintained until then collapsed, and nations launched new wars for world hegemony.
In this great war, the Japanese Federal Republic, the Kingdom of Howell, and the Schwarzwald Empire emerged as the final three victors, while other nations were absorbed into various factions, and some chose neutrality to stay away from the flames of war. The world situation was thus completely transformed.
Afterwards, the three great powers, exhausted by the prolonged war, temporarily ceased hostilities to avoid repeating past mistakes, and the world entered a state of Cold War.
However, facing a world maintained by a balance as fragile as thin ice and on the verge of collapse at any moment, nations dared not be negligent in conscription and weapons development, continuously engaging in an arms race in preparation for new wars.
Subsequently, a new research achievement was born in the world: an innovative technology codenamed "IOS," operated through a universal weapon operating system called the "Interoperate System."
If this device, which simplifies the necessary procedures for using weapons and allows even those without specialized knowledge to operate any weapon at will, were to be put into practical application, the time spent on operational training and the minimum number of personnel required to use weapons would be drastically reduced, giving birth to the ultimate all-purpose soldier capable of commanding all land, sea, and air weapons.
However, IOS has the restriction that it cannot be used by those who are not adapted to it.
This story begins with the daily life of the protagonist, who belongs to a regular army unit of the Japanese Federal Republic and possesses IOS adaptability, as he completes his missions.