Meer

Meer is Rean Cropp's pet dog.

Appearance
Meer is a small dog with thick white fur, a roundish body and head and a short snout and tail. Their build could most accurately be described as that of a Japanese Spitz or Pomeranian, but it's never clearly stated in the manga or anime which breed of dog Meer belongs to. They wear a collar with a metal plate on which their name is engraved around their neck.

They can usually be seen with their tongue sticking out.

Personality
Meer is a friendly dog that's never seen barking at strangers. They seem very trusting as well, approaching Gugu without fear (probably because they smelled his food) and following him to the market the next day. Because of their rather mellow or even passive personality, Meer isn't seen or heard defending Rean when a man hired by her father tries to capture her, either.

Background
Meer is Rean Cropp's pet dog. It's unknown at what age she adopted Meer.

Judging by their size, Meer was already an adult dog by the time they first appeared in the manga.

Plot
Meer first appears when they meet Gugu near his home and beg for food. The next day, they follow him to the market where Meer's owner, a girl later revealed to be called Rean Cropp, has already been searching for them for several days. After realizing this, Gugu promptly returns Meer to their owner.

After Gugu runs away from Booze Man's tower and is later rescued by Fushi, Meer runs away from Rean, too, and joins Fushi and Gugu in the forest to eat the food Fushi created.

Meer can be seen various times throughout the story, mostly while he's being carried by or walking alongside Rean or Gugu.

Rean Cropp
Rean is Meer's owner who cares about them very much. Even if motivated by other reasons, she goes looking for Meer herself every day after he's gone missing.

Gugu
Gugu and Meer first meet near the tent in which Gugu and his brother Shin live. He shares his steamed bun with Meer and the next day, the dog follows him to the market in hopes of more food. Gugu finds out that Meer belongs to Rean and gives them back to her, who gifts him a highly valuable ring in thanks.

While Gugu regains his strength after being saved by Fushi from kidnappers, Meer finds him again, possibly attracted by the food Fushi created. By following Meer, Rean finds him, too, and manages to convince Gugu to come back to Booze Man's tower.

While Meer might not seem to play a big role in the story, it's their tendency to run away that allowed Rean and Gugu to meet in the first place.