The story takes place in a real world that strictly follows classical mechanics, low-speed macro, and quantum and relativity never intervene.
The girl Kai relies on her ultimate force analysis and mechanical thinking, and uses physical laws such as leverage, collision, and resonance to solve seemingly unsolvable puzzles and crises one after another.
She will not give up and move toward tomorrow, because the person she was yesterday has used every force calculation to reach today.
Purpose: Full marks in mechanics