Story

Bubbles is North Kai's pet.
Since Bubbles resides on the Planet of the Kai, which has 10 times the gravity of Earth, he is super fast!

Goku comes to train under the pun-loving Kai, but tells the warrior, "Until you can overcome this gravity... There's no point in anything else!" He then has Goku try to catch Bubbles as his first lesson!

(Tale 211)

Bubbles monkeys around with Goku with ease, as the gravity doesn't bother him!

(Tale 211)

Even after removing his heavy training uniform and eating his fill to refresh himself, Goku still couldn't catch Bubbles!

(Tale 211)

After forty days or so, Goku finally adjusts to the gravity and manages to get his hands on the speedy primate!

(Tale 211)

Piccolo, Yamcha, Tenshinhan, and Chaozu all go to North Kai's planet as well during the Frieza Arc after dying in the midst of the Saiyan invasion.
Yamcha and crew also train hard to be able to catch Bubbles.

(Tale 263)

During the Cell Arc, Goku uses Transportation to bring Cell to the Planet of the Kai in order to save Earth from Cell's self-destruction.
Unfortunately, Bubbles gets caught up in the blast and tragically loses his life... However, since Bubbles was already a resident of the heavenly realm, the only result was that he got a shiny new halo.

(Tale 413)

First Appearance

"Dragon Ball" Tale 210

Goku Confuses Bubbles for North Kai!

When Goku first arrives at the Planet of the Kai, he mistakenly thinks that Bubbles is North Kai! He even does a proper formal introduction, then proceeds to copy the monkey's movements and shout, "Ooka.. Ooka..!!" as part of what he assumed to be some kind of training!

(Tale 210)

→Preview: Scroll down to the comments for a hint about who next week's character will be!

*All images are from the Japanese version.