Since she's be central to the plot of the Disney film "The Black Hole", would that make Black Hole-sensei a Disney Princess?
Both Black Hole Sensei and...I guess "M87-Sama" by default scream bloody murder to all stars. Having a Disney Princess villain would be a treat, wouldn't it?
The densest girl in the universe. But would she be denser than harem Protags?
The Swarzschild radius of a black hole is a linear function of its mass, whereas volume is a cubic function of radius. So a black hole gains volume faster than it gains mass, and larger black holes have a lower average density than smaller ones. M87* has an average density of about 170 kg/m^3, which is about one-sixth the density of water.