She’s incredibly smart, but pretends to be stupid. Junko's personality is very apathetic and easily bored to an unhealthy and abnormal degree. Because of this, her behavior and mannerisms tended to be extremely erratic and unstable by her own autonomous design; keeping up one "appearance" for too long bores her, which causes her to often switch between different personas suddenly. She’s actually the self proclaimed Ultimate Despair, she’s running a killing game, to bring despair to the world.