故事开始于两个人面对面坐在一张长桌子对面。突然，两个人中的一个开始向另一个人扔球。而这种投掷，只是单向的，演变成了双向的投掷……

The story begins when two people sit facing each other across a long table. Suddenly, one of the two people starts to throw a ball to another person. And this throwing, which was just a one-sided, evolve into two-way throwing...