In "This Is The Happiness And Peace Of Mind Committee" Miku appears to be the spokesperson for the Committee, forcing their citizens to pretend to smile and be happy. Anyone who fails to comply is executed, and you can hear roaring brainwashed crowds behind her.
The lyrics tell everyone that being happy is their duty, and that the Happiness and Peace of Mind committee will support them.
The song's tone changes dramatically from beginning to the end to sing the truth of how people feel.
from vocaloid.fandom.com