202X, the world where the rate of smartphones has expanded further than it is now. The act of operating a smartphone while walking, the so-called "walking smartphone," has become a social problem due to the large number of accidents, and the "walking smartphone ordinance" that regulates it has been introduced.

It is said that a well-behaved citizen selected from the country can act as a private observer and give caution and punishment on the spot to people who are walking smartphones.

One day, due to some mistake, a half-enclosed letter arrives at me. There was a passcard inside and a sentence attached to it.

Walking smartphone ordinance, appointing observer