Robodog, formally designated Robodog No. 1 or Robodog-Dog No. 1 (ロボドッグ犬1号), is a robotic creation manufactured at the King's Idea Laboratory under Dr. Eyepatch's supervision. His primary function is to assist during missions assigned to Milk Chan and her companions. Robodog consistently exhibits a rude and disruptive personality, frequently causing conflicts and complications during operations. A defining characteristic is his incontinence, manifesting as severe bladder control issues, which fuels his unpredictable and troublesome behavior.

He maintains a bitter rivalry with the robotic maid, Tetsuko. Their antagonistic relationship stems from competing for Milk Chan's attention and favor, often escalating into arguments and interference during missions, creating recurring friction within the group. Robodog debuted in the inaugural episode of "OH! Super Milk Chan," titled "The Evil Spirits Go Marching In" (also known as "The Trouble with Money" in the Americanized dub), participating in the mission to apprehend a counterfeiter.

Across subsequent episodes, seasons, and official media, no significant character development, background expansion, or alterations to his core traits occur. His role remains consistent as a mission assistant whose flaws and antagonism toward Tetsuko drive conflict. He is designated "Robodog 1000" in the Americanized English dub and "Perrobot" (a portmanteau of Spanish "perro" and "robot") in the Latin Spanish dub. His preferred sustenance is mechanical bones.