The year is 202X, in a world where the prevalence of smartphones has expanded even further than it is today. The act of operating a smartphone while walking, the so-called "walking smartphone," has become a social problem due to the number of accidents, and the "walking smartphone ordinance" has been introduced to regulate this behavior. The ordinance allows government-selected, well-behaved citizens to act as private watchdogs and issue on-the-spot warnings and punishments to people who are walking while using their phones. One day, by mistake, a letter arrives at my doorstep as a semi-reclusive person. Inside was a pass card and a letter. I'm appointed as a "walking smartphone ordinance watchdog"...