in far future

From their return from military training, cadets of space defence university find themselves witnesses of the occupation of their home planet Kibi. The agressor is Henrietta, Alliance of Planetary Nations, which id for its practices and expansion called the Kingdom.

Entire crew except the cadets are ordered to leave Amaterasu returning from the training. The remaining cadets decide to take a step and knowing the ship will be sold to a company and then resold for the resources to the Kingdom. They find a sponsor and buy Amaterasu before the enemy.

Modern battleship Amaterasu and its non-experienced crew decide to fight against the occupants of their world, but the have only one ship against whole army...