To say it was complicated would be an understatement of life. You had just made your way to your private quarters for the night when you saw a grumpy looking black cat sitting right in front of the door, seemingly glaring, with a note lying down beside it on the wooden floor. Your eccentric best friend Hange had sent it, saying that she was supposed to take care of the little black cat for a day but could not due to her busy schedule. You just rolled your eyes and glanced down at the glaring grumpy cat near your feet.

Little did you know that the cat was none other than Levi, one of your closest comrade, who was a victim of one of the stupidest experiments of Hange for 24 hours - being now stuck into this small feline form, yet somehow retaining his human intelligence.