The Little Bunny refers to an animal in which Crona was forced to kill by Medusa Gorgon, thus making the animal the one of the first of Crona's victims. In the anime, the animal is a Dragon and is renamed The Little One.
The Little Bunny appeared as a harmless white rabbit and was small in size, much like it's named implied. In the anime, the creatured appears as a a small, black Dragon instead with red eyes, wings, and a horn on top of it's head in which sticks upward like that of a cone.
As a Dragon in the anime, the Little One had the basic ability to breathe fire and most likely had the ability to fly with the usage of it's wings.
During Crona's childhood, the meister was ordered by Medusa Gorgon to kill the bunny. However, Crona was troubled by this, stating that they "Didn't know how to deal with this". This promptly caused Crona to be imprisoned in a dark room for a couple days. After several days, Crona once again approached the bunny and killed the animal with Medusa remarking that they were having bunny for dinner.
- A humorous detail is that, on the back of Volume 5, there is a picture of the Little Bunny holding a large knife with the caption 'revenge'. This is most likely an additional image by Atsushi Ōkubo, for they are often included before the contents page and on the back under the blurb.
- While unconfirmed currently, the Little Bunny's change from a bunny to a dragon may have been for censorship reasons.