Explanation: An early quest in Elona is given by Rilian the Dog Lover to bring her Poppy, the lost puppy from the Puppy Cave. (This is a direct homage to ADOM, where you have to save a Cute Dog for a Tiny Girl.)
This player is obviously having a little trouble getting the exact requirements here right...
(Note: Because of the way the dungeon resets each time you change a floor, and the puppy's level 1 status, it's easy for the dog to get killed by random monsters that spawn again as you ascend towards the exit. If you fail the quest by letting the dog die, however, the dog can simply be found again at the fifth and bottom floor of the dungeon.)
Kobolds, like here, are common low-level enemies that are easy to capture.
On Pixiv the artist said the player messed up and the puppy died in the cave. He didn't know what to tell Rilian and so he caught that beast and tries to tell her that's the puppy.. or at least a substitute.