CHRV-138 20XX capital blockade! What happened in a closed-door single-parent family with only three

One day, my sister suddenly rushed to the place where my father and brother were looking out the window from a high-rise apartment and talking about something strange about the city today! It seems that Tokyo has just been blocked suddenly ... The entrance to the condominium is also blocked and guards are watching ... Of course, the elevator doesn't work and the emergency stairs can't be used ... What will happen after this ...