A young girl is worried about how her pet jabberguppy is coping since she became a ghost.
This errand is available to complete after defeating Cap'n Crossbones and arriving at Yule.
To start this errand, you have to return to Sleety Hollow, which was the hidden cave you visited earlier to the southeast of Yule. Return there by having Tengri drop you off in the open area just to the north of the large ice chunks, then enter the cave. Talk to the girl in here using Spirit Medium, and you'll find out that she just wants you to toughen her pet jabberguppy up so that it can move on without her.
To complete this task, you must level up the Jabberguppy from 30 to 40. You can either just throw it in your party and come back once the time comes, or you can take it just outside of Perdida near Billy Goat's Bluff and fight four Tokotokos to get there. Either way, once you're at 40, she'll reward you and this errand will come to a close, with you keeping the pet familiar.