Here is a list of Nine Inch Nails songs that need to appear in Unikitty 2019 episodes.
Hurt: when Unikitty is sad.
Mr. Self Destruct: when Master Frown appears.
Heresy: when Hawkodile is angry.
Eraser: when Dr. Fox is angry.
Piggy: when Puppycorn is angry.
I Do Not Want This: when Master Frown is knocking on Unikitty's door.
March of the Pigs: When Unikitty is held captive in Master Frown's lair.
Closer: when Richard's happy.
These songs are the best.