Superheroes mean different things to different people. For Akira, they represent the pleasant memories and dreams of his childhood. To Shizuka though, superheroes represent an ideal that can never be achieved, and one which is only sought as a form of escapism by people who are unhappy with their life as it is.
Source:https://www.cbr.com/zom-100-akiras-dream-calls-into-question-the-psychology-of-superheroes/