The series works under a sliding timescale where the characters have maintained their ages throughout the course of the series. Though time has passed to allow for the rise and fall of several pop culture icons, marriages, pregnancies, and births of various characters, all the characters still maintain their age at the time of their introduction. For example, if the two major births in the series are taken into account (Shinnosuke's sister, Himawari, and his kindergarten teacher's child), Shinnosuke would be seven years old and in second or third grade, but he is not.