Sombrenosuke serves as one of three primary robotic protagonists coexisting with humans in their shared world. This character operates within a defensive trio alongside Nejimaru and Drum-Kan-Be, collectively safeguarding against external threats. When the extraterrestrial invasion force Corporation Baddoru arrives to conquer Earth, Sombrenosuke and his companions unite to confront this adversary, directly opposing the Baddoru Corps' campaign for universal domination.

The robot's stylized design incorporates a dot-matrix LCD screen that visibly conveys emotional states. During confrontations with antagonists, Sombrenosuke exhibits a distinctive glowing effect.

No concrete information exists regarding the character’s specific background, individual development, or expanded storylines in supplemental media such as films, OVAs, or spin-offs. Available details exclusively pertain to Sombrenosuke’s role in the core conflict against the Baddoru invasion.