Gatchan, also known as Gadzilla Norimaki, is a cherub-like being adopted by the Norimaki family after hatching from an egg Senbei Norimaki brought from the prehistoric era. Arale Norimaki named them by blending "Gamera" and "Gojira" (Godzilla), inspired by her love of monsters.

Resembling a small, wingless infant, Gatchan has green hair, antennae, and no defined gender. They communicate through "Gatchanism," a unique language only Arale comprehends. Gatchan exhibits a voracious appetite, devouring nearly anything except rubber while favoring metal. Their antennae unleash destructive beams, typically for defense.

Sharing Arale’s playful and innocent nature, Gatchan frequently accompanies her on escapades. Key capabilities include flight, resilience to high falls, and survival without visible injury. In "Dr. Slump & Arale-chan Hoyoyo!! Tasuketa Same ni Tsurerarete...," Gatchan joins Arale’s family on an underwater kingdom visit after Arale rescues a baby shark, with no further elaboration on their role.

Gatchan’s origins reveal they are an angel sent by Kami, the galaxy’s ruler, to obstruct human technological progress by consuming metal resources. Senbei’s intervention thwarted this mission, leading Kami to spare Earth upon seeing Gatchan’s contentment with the Norimakis. Later, Gatchan metamorphoses via a chrysalis into identical twins—Gatchan #1 and #2. Future developments show them multiplying into eight individuals, with hints of ongoing proliferation.

The character appears across media, including "Dr. Slump" video games and "Dragon Ball" titles like "Dragon Ball Z: Budokai Tenkaichi 3," where they aid Arale in combat. The 1997 "Dr. Slump" remake depicts Gatchan emerging from a machine with blonde hair instead of green. Live-action promotions, such as a G.U. fashion commercial, feature Gatchan flying alongside other characters.