Gajira Norimaki, almost universally called Gatchan, is a small, cherubic creature who is a member of the Norimaki family in Penguin Village. This character has a small, childlike body, complete with wings and short antennae on the head. The hair is typically depicted as a thick head of green or blonde curls, and the usual outfit is a simple baby's onesie with a bib and small boots.

The origin of Gatchan is extraordinary and is revealed to be divine. Senbei Norimaki, the village inventor, discovered a strange egg during a time-travel trip to the prehistoric era and brought it back to the present. When this egg hatched, Gatchan emerged. It is later disclosed that Gatchan is actually an angel, sent to Earth long ago by the god of the galaxy. The original mission was to prevent human civilization from developing too far or destroying itself, with the creature's immense appetite for metal intended to consume technological resources. This mission ultimately fails due to its integration into modern Penguin Village, but the galaxy god, after observing the peaceful and happy life of the villagers, decides to spare humanity.

In terms of personality, Gatchan exhibits the innocent and playful nature of a very young child. Communication is handled through a unique, expressive language of sounds like pupipopipi, which Arale Norimaki intuitively understands. The creature is defined by a voracious and indiscriminate appetite. While almost anything can be consumed, there is a particular fondness for metal and a notable aversion to rubber. This appetite is not merely a quirk but is tied directly to the original angelic purpose of hindering technological progress.

Gatchan possesses several notable abilities. Flight is possible thanks to the small wings on the back. A more combative skill is the Antenna Beam, an energy ray that can be fired from the antennae for self-defense or assistance in adventures. The most defining biological ability, however, is asexual replication. After consuming an enormous amount of food, Gatchan once spun a cocoon and, after a period of two weeks, emerged as two separate but perfectly identical beings. From that point on, they are collectively known as the Gatchans, functioning as a pair.

Within the story, Gatchan serves primarily as a constant companion and a surrogate younger sibling to the main character, Arale Norimaki. The name Gajira itself is a name Arale gave, blending the names of the iconic kaiju Gamera and Gojira (Godzilla). The two Gatchans are almost always seen with Arale, cheerfully participating in her bizarre games, accompanying her on trips, and even aiding her in confrontations. In crossover appearances within the Dragon Ball series, the Gatchans have been shown assisting Arale in battles against characters like General Blue and Tao Pai Pai. The primary family relationships are with Senbei Norimaki (the adoptive father who hatched them), Arale (the adoptive sister and best friend), and Midori Norimaki (the adoptive mother).

In the specific film Dr. Slump & Arale-chan Ncha! Wakuwaku Hot Natsu Yasumi, Gajira Norimaki appears as a supporting character in the standard role as part of the Norimaki family. The plot involves the family and their neighbors going on a summer vacation to what they believe is a resort, only to discover it is a haunted castle ruled by a female vampire named Vandora. Throughout the larger narrative spanning the Dr. Slump manga and anime, Gatchan does not undergo significant emotional development but remains a static figure of pure, metal-eating innocence. The only major change is the physical division from one entity into a pair, which then persists as the permanent status quo for the rest of the series.