"I'm the world-famous Junko Kurosu, a genius thespian surpassing even Marilyn Monroe!"
"An actress who caused a stir around ten years ago. She retired due to a scandal, but has made a comeback, looking remarkably unchanged."
"The last member of the Masked Four, in possession of the wind skull. It seems she was mainly gathering Ideal Energy from adults."
Junko was once a popular student in the Seven Sisters High School, who later became an actress. When Jun was born, she mostly ignored him and was a distant mother. She and her husband fought and argued constantly. When his home life got worse and worse, Jun began to hate both his mother and father. Junko began to miss her life as a celebrity.
Junko became tired of her husband and got suspicious of his relationship with Maya Okamura, hiring Daisuke Todoroki to follow them, to no avail. She eventually began spreading rumors about him, partly aiding in his death at Seven Sisters High's clock tower. Junko is later revealed to be Queen Aquarius of the Masked Circle, having joined after she made a wish to Joker for eternal youth.
She eventually learned that her own son, Jun Kurosu, was, in fact, Joker himself. Moments after this revelation and the realization of how horribly she had mistreated him, she shoved him out of the way of a Longinus spear aimed for him, taking the blow herself and dying as a result. Thus, she is never fought directly.
She was later summoned by Nyarlathotep to be tortured in front of her son along with her husband just before the final battle. Junko apologizes to Jun for only caring about her dreams and being blind to everything else. Following Nyarlathotep's defeat, she was revived with no memory of her past misdeeds in the alternate timeline created by the party to allow Maya Amano to survive.
Junko appears indirectly as the enemy Metal Mama in Xibalba as a manifestation of Jun's anxiety. Metal Mama claims Jun and Akinari were burdens, and her life would be better if Jun was never born, and that as his mother, she can do whatever she wants to him.
"Her real name is "Junko Kashihara". She's a huge star and mother of Jun Kashihara. I feel I know her..."
In the alternate timeline, her husband was still alive and her life with him was a better one. However, Chizuru Ishigami infects her with the JOKER curse. She attacks Tatsuya on Chizuru's command, but is knocked out and cured off screen.
Junko as she appears when she's dying and with eternal youth
Junko as she appears looking worried and as Queen Aquarius
Metal Mama's portrait
Junko Kurosu as a Joker
Queen Aquarius' portrait
Queen Aquarius as she is dying
Junko's portrait from Innocent Sin
Junko's sad portrait
Junko's portrait from the ending of Innocent Sin
Metal Mama's portrait
Metal Mama's sprite